1. science
2. physics

ii
ICOLS 2015
22nd International Conference on
Laser Spectroscopy
June 28 - July 3, 2015
Sentosa Island, Singapore
iv
Table of Contents
1 Program Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
2 Invited Talk Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . .
7
Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
v
vi
1. Program Overview
The conference starts with a welcome reception and registration on Sunday June 28,
starting at 18:30hr, at the Siloso Beach area of the Rasa Sentosa Resort. The sessions
will start in the morning of Monday, June 29 and will end on Friday, July 3 around
noon time. There will be keynote talks, invited talks, and hot topic presentations
of durations 45, 30, and 25 minutes, respectively (including 5 minutes of question
time). All talks will be held at the Horizon Pavilion on level 5 of the Shangri-La’s
Rasa Sentosa Resort & Spa, Singapore. Coffee breaks will be either at the lounge
area outside the Horizon Pavilion on level 5 or outside the Siloso 1 & 2 function
rooms on level 1, if preceding the poster sessions. There will be lunch buffet at the
restaurant at the Silver Shell Cafe on level 3, which is included in the conference fee.
A public evening lecture will be given by Alain Aspect on Wednesday at 19:00, at
the Singapore Science Centre. Poster sessions are on Monday and Tuesday. Tours
of local labs are offered on Friday afternoon. Excursions into Singapore are on
Wednesday afternoon, and the conference banquet will take place at the Marina Bay
Sands Expo and Convention Centre on Thursday evening at 19:00hr.
Sunday, June 28, 2015
18:30 - 20:30 , Welcome Reception and Registration, Siloso Beach at Rasa
Sentosa Resort
Monday, June 29, 2015
8:50 - 10:45
Precision I
Horizon Pavilion
Chair: TBA
Opening Remarks
Eric Cornell - TBA - (45 min., )
Gerald Gabrielse - TBA - (45 min., )
10:45 - 11:15, Coffee
Lounge outside Horizon Pavillion
1
Tuesday, June 30, 2015
11:15 - 12:25
Ion Trapping
Ch.1. Program Overview
Horizon Pavilion
Chair: TBA
Richard Thompson - Optical Sideband Cooling of Ions in a Penning Trap - (30 min.,
p.8)
Tobias Schaetz - Trapping Ions Atoms and Molecules Optically - (30 min., p.9)
Dzmitry Matsukevich - Degenerate parametric down-conversion with phonons in
the ion trap. - (25 min., p.10)
12:25 - 14:00, Lunch
Silver Shell Cafe
14:00 - 15:45
Horizon Pavilion
Chair: TBA
Precision II
Dmitry Budker - Optical magnetometry: from zero-field nuclear magnetic resonance to searching for axion-like dark particles - (45 min., p.11)
Marianna Safronova - Highly-charged ions for atomic clocks, search for α-variation,
and tests of Lorentz symmetry - (30 min., p.12)
Hartmut Haeffner - A Michelson-Morley test for electrons using trapped ions (30 min., p.13)
15:45 - 16:15, Coffee
Siloso Function Room
16:15 - 22:00
Siloso Function Room
Poster I
Tuesday, June 30, 2015
9:00 - 10:45
Clocks
Horizon Pavilion
Chair: TBA
Ekkehard Peik - Optical clocks with trapped ions - (45 min., p.14)
Hidetoshi Katori - Frequency ratios of Sr, Yb, and Hg based optical lattice clocks
and their applications - (30 min., p.15)
Jun Ye - High accuracy atomic clock and its probe of quantum many-body physics (30 min., p.16)
2
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.1. Program Overview
10:45 - 11:15, Coffee
Wednesday, July 1, 2015
Lounge outside Horizon Pavillion
11:15 - 12:15
Quantum Networks
Horizon Pavilion
Chair: TBA
Nicolas Treps - Quantum networks with optical frequency combs - (30 min., p.17)
Pepijn Pinkse - Adaptive Quantum Optics and its Application: Quantum-Secure
Authentication - (30 min., p.18)
12:15 - 14:00, Lunch
Silver Shell Cafe
14:00 - 15:45
Horizon Pavilion
Chair: TBA
Atom Interferometry
Mark Kasevich - TBA - (45 min., )
Gabriele Rosi - Precision measurement of the Newtonian gravitational constant by
atom interferometry - (30 min., p.19)
Nicholas Robins - The generation and use of solitonic matter-waves in atom optics
- (30 min., p.20)
15:45 - 16:15, Coffee
Siloso Function Room
16:15 - 22:00
Siloso Function Room
Poster II
Wednesday, July 1, 2015
9:00 - 10:45
Optical Lattices I
Horizon Pavilion
Chair: TBA
Immanuel Bloch - From Many-Body Localization to Novel Rydberg Quantum
Magnets - New Frontiers for Ultracold Quantum Gases - (45 min., p.21)
Jean Dalibard - Cold atomic gases in a flat box:
A new window on quantum many-body physics - (30 min., p.22)
Ana Maria Rey - New frontiers in quantum simulation enabled by precision laser
spectroscopy - (30 min., p.23)
ICOLS 2015, Singapore, June 28 - July 3, 2015
3
Thursday, July 2, 2015
10:45 - 11:15, Coffee
11:15 - 12:15
Optical Lattices II
Ch.1. Program Overview
Lounge outside Horizon Pavillion
Horizon Pavilion
Chair: TBA
Randall Hulet - Antiferromagnetism with Ultracold Atoms - (30 min., p.24)
Andrea Alberti - Quantum walks with neutral atoms - (30 min., p.25)
12:15 - 14:00, Lunch
Silver Shell Cafe
14:00 - 18:00, Excursions
19:00, Public evening talk
Alain Aspect, Title: TBA
Singapore Science Center
Thursday, July 2, 2015
09:00 - 10:45
Precision III
Horizon Pavilion
Chair: TBA
Aldo Antognini for the CREMA collaboration - Spectroscopy of muonic atoms
and the proton radius puzzle - (45 min., p.26)
Eric Hessels - Helium n=2 triplet P fine structure, quantum-mechanical interference
shifts, and frequency-offset separated oscillatory fields - (30 min., p.27)
Livio Gianfrani - The Boltzmann constant from the shape of a molecular vibrationrotation transition - (30 min., p.28)
10:45 - 11:15, Coffee
11:15 - 12:15
Photonics Systems
Lounge outside Horizon Pavillion
Horizon Pavilion
Chair: TBA
Arno Rauschenbeutel - Chiral interaction of light and matter in confined geometries
- (30 min., p.29)
Martin Weitz - Coherence of a Bose-Einstein Condensed Light Field - (30 min.,
p.30)
4
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.1. Program Overview
Friday, July 3, 2015
12:15 - 14:00, Lunch
Silver Shell Cafe
14:00 - 15:45
Horizon Pavilion
Chair: TBA
Ultrashort and Applications
Chang Hee Nam - High Harmonic Spectroscopy of Molecules - (45 min., p.31)
Aleksei Zheltikov - Laser-induced filaments in the mid-infrared - (30 min., p.32)
Vincent Daria - Light-Neuron interactions: Key to understanding the brain - (30 min.,
p.33)
15:45 - 16:15, Coffee
Lounge outside Horizon Pavillion
16:15 - 17:30
Horizon Pavilion
Chair: TBA
Hot Topics
Tanya Zelevinsky - Subradiant molecular lattice clock - (25 min., p.34)
Daniel McCarron - Improved Magneto-optical Trapping of a Diatomic Molecule (25 min., p.35)
Marc Cheneau - Atomic Hong-Ou-Mandel Experiment - (25 min., p.36)
19:00, Conference banquet
Marina Bay Sands Expo Center
Hibiscus Ballroom
Friday, July 3, 2015
09:00 - 10:45
Horizon Pavilion
Chair: TBA
Quantum Control
Gerhard Rempe - Quantum Nonlinear Optics for Quantum Science - (45 min., p.37)
Jakob Reichel - Quantum engineering and metrology with
Fiber Fabry-Perot microcavities - (30 min., p.38)
Gerd Leuchs - TBA - (30 min., )
10:45 - 11:15, Coffee
Lounge outside Horizon Pavillion
11:15 - 12:25
Photon Entanglement
ICOLS 2015, Singapore, June 28 - July 3, 2015
Horizon Pavilion
Chair: TBA
5
Friday, July 3, 2015
Ch.1. Program Overview
Jian-Wei Pan - TBA - (30 min., )
Yoon-Ho Kim - Engineering Frequency-Time Quantum Correlation of Narrow-Band
Biphotons from Cold Atoms - (30 min., p.39)
Closing remarks
12:25 - 14:00, Lunch
Silver Shell Cafe
14:00 - 17:30, Tours of local laboratories
6
ICOLS 2015, Singapore, June 28 - July 3, 2015
2. Invited Talk Abstracts
7
Ch.2. Invited Talk Abstracts
Monday, 11:00
Optical Sideband Cooling of Ions in a Penning Trap
Richard Thompson
Blackett Laboratory, Imperial College London, London SW7 2AZ, UK
Optical sideband cooling of trapped ions to the ground state of their motion is now a
standard technique. This is a pre-requisite for experiments in trapped ion quantum
information and quantum optics. Until now optical sideband cooling has not been
demonstrated in a Penning trap. This is because the presence of the magnetic field
complicates the laser requirements considerably. However, it is desirable to achieve
this because the Penning trap may give much lower anomalous heating rates than
radiofrequency (RF) traps, due to the relatively large size of the electrodes and the
absence of effects due to the RF fields.
We work with Doppler cooled calcium ions in a Penning trap with a magnetic
field strength of 1.85 T. This requires two lasers at 397 nm, four laser frequencies at
866 nm, and up to eight laser frequencies at 854 nm. We have prepared Coulomb
crystals of up to many hundreds of ions. We can control the conformation of these
crystals through variation of the trap parameters, from linear chains of up to 30 ions,
through a range of three-dimensional structures to two-dimensional planar sheets.
We have recorded spectra of the optical qubit transition in calcium at 729 nm
using a highly-stabilised diode laser having a linewidth around 1 kHz [2]. These
spectra show that the axial motion reaches the expected Doppler limit of about 0.5
mK. We are also able to measure the temperature of the two radial motions and we
have shown for the first time that the magnetron motion reaches a temperature of a
few tens of µK when Doppler cooled with a radially inhomogeneous beam.
We have now used the same 729 nm laser to sideband cool the axial motion of a
single ion, achieving a 98.7% probability of occupation of the ground state [3]. We
also demonstrated that the anomalous heating rate is among the lowest measured for
an ion in a room temperature trap, consistent with the large electrode-ion distance.
At the conference we will report the latest results of this work.
1.0
Excitation Probability
0.9
HaL
HbL
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-410
Detuning from carrier HkHzL
-390
-370
370
390
410
Figure 1: (a) First red and (b) first blue sidebands after sideband cooling.
References
[1] S. Mavadia et al., Nature Communications 4, 2571 (2013).
[2] S. Mavadia et al., Phys. Rev. A 89, 032502 (2013).
[3] J. F. Goodwin et al., arXiv:1407.6121 (2014).
8
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Monday, 11:30
Trapping Ions Atoms and Molecules Optically
Tobias Schaetz
Albert Ludwigs University Freiburg, Hermann Herder Str 3, Germany
Isolating ions and atoms from the environment is essential in experiments on a quantum level. For decades, this has been achieved by trapping ions with radiofrequency
(rf) fields and neutral particles with optical fields. Our group demonstrated the
trapping of ions by interaction with light [1,2]. We take these results as starting point
for finally combining the advantages of optical trapping and ions [3]. In particular,
ions provide individual addressability, high fidelities of operations and long-range
Coulomb interaction, significantly larger compared to those of atoms and molecules.
We aim to demonstrate the improvement of our approach in the context of interaction and reaction at ultra-low temperatures as a showcase. Following the seminal
work in the groups of Vuletic, Koehl and Denschlag in hybrid traps, we plan to embed
optically trapped ions into quantum degenerate gases to reach lowest temperatures,
circumventing the currently inevitable excess kinetic energy in hybrid traps, where
ions are kept but also driven by rf-fields [4]. It might permit to enter the temperature
regime where quantum effects are predicted to dominate, (i) in many-body physics,
including the potential formation and dynamics of mesoscopic clusters of atoms [5]
of a BEC, binding to the impurity ion, as well as (ii) the subsequent two-particle
s-wave collisions, the ultimate limit in ultra-cold chemistry. We will report about our
recent results [6] on optically trapping 138 Ba+ in a far-off-resonant dipole trap and
87 Rb atoms in a MOT in our laboratory.
References
[1] C. Schneider, M. Enderlein, T. Huber, and T. Schaetz, Nature Photonics 4, 772 (2010).
[2] M. Enderlein, T. Huber, C. Schneider, and T. Schaetz, Phys. Rev. Lett. 109, 233004 (2012).
[3] C. Schneider, D. Porras, and T. Schaetz, Reports on Progress in Physics 75, 024401 (2012).
[4] M. Cetina, A. T. Grier, and V. Vuletic, Phys. Rev. Lett. 109, 253201 (2012).
[5] R. Cote, V. Kharchenko, and M. D. Lukin, Phys. Rev. Lett. 89, 093001 (2002).
[6] T. Huber, A. Lambrecht, J. Schmidt, L. Karpa, T. Schaetz, Nature Communications, 5 (2014).
ICOLS 2015, Singapore, June 28 - July 3, 2015
9
Ch.2. Invited Talk Abstracts
Monday, 12:00
Degenerate parametric down-conversion with
phonons in the ion trap.
Dzmitry Matsukevich
Centre for Quantum Technologies, National University of Singapore, 3 Science Dr 2, 117543,
Singapore
Department of Physics, National University of Singapore, 2 Science Dr 3, 117551, Singapore
Ions confined in a Paul trap are isolated from environment and their motion is usually
well approximated by a set of normal modes. However the Coulomb interaction
between the ions is not linear and can introduce coupling between these modes [1,2].
In this talk we report experimental investigation of the coupling between outof-phase axial and radial modes of motion in a system of two trapped Yb171 ions
under the resonance conditions, when the frequency of the radial mode is twice the
frequency of the axial mode. Hamiltonian of the system in this case is similar to the
Hamiltonian of the degenerate parametric down conversion. We observe oscillations
between the phonon population in radial and axial modes of motion if the radial
mode had initially two phonons and the axial mode was cooled to the ground state,
and absence of oscillations if the radial mode had only one phonon.
We use this coupling to perform adiabatic transfer of quantum states between
the modes, determine a parity of the motional state in the radial mode and directly
measure a Wigner function of the ion motion.
References
[1] C. F. Roos, et al. Phys. Rev. A77, 040302 (2008)
[2] X. Nie, C. F. Roos, and D. James, Phys. Lett. A 373, 422 (2009).
10
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Monday, 14:00
Optical magnetometry: from zero-field nuclear
magnetic resonance to searching for axion-like dark
particles
Dmitry Budker
Helmholtz Institute, Johannes Gutenberg University, Mainz, Germany
University of California and Nuclear Science Division, LBNL, Berkeley, California, USA
I will discuss results obtained in the past several months using laser-based atomic
and color-center magnetometry to detect nuclear magnetic resonance at zero and
near-zero magnetic fields (“NMR without magnets”). Another emerging application
is detectinc transient and oscillating quasi-magnetic fields that may be a signature
for certain theoretically plausible constituents of dark matter and dark energy. Upto-date references for the work in these areas involving our group can be found at
http://budker.berkeley.edu/ and https://budker.uni-mainz.de/ .
ICOLS 2015, Singapore, June 28 - July 3, 2015
11
Ch.2. Invited Talk Abstracts
Monday, 14:45
Highly-charged ions for atomic clocks, search for
α-variation, and tests of Lorentz symmetry
Marianna Safronova
Department of Physics and Astronomy, University of Delaware, Newark, Delaware, USA
Joint Quantum Institute, NIST and the University of Maryland, College Park, Maryland, USA
The modern theories directed toward unifying gravitation with the three other fundamental interactions suggest variation of the fundamental constants in an expanding
universe. Development of optical atomic clocks allowed laboratory tests of the variation of the fine-structure constant α. Selected transitions in highly-charged ions were
shown to have very large sensitivities to α-variation. Moreover, some highly-charged
ions have level structure and other properties that are not present in any neutral and
low-ionization state ions that may be advantageous for the development of atomic
clocks and provide remarkable new opportunities for precision tests of fundamental
science and quantum information. I will give an overview of various highly-charged
ion systems proposed for these applications and discuss Ag-like, Cd-like, In-like,
and Sn-like ions [1] in more detail. Proposals for tests of Lorentz symmetry with
highly-charged ions and Yb+ are presented.
References
[1] M. S. Safronova, V. A. Dzuba, V. V. Flambaum, U. I. Safronova, S. G. Porsev, and M. G. Kozlov, Phys.
Rev. Lett. 113, 030801 (2014).
12
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Monday, 15:15
A Michelson-Morley test for electrons using trapped
ions
Hartmut Haeffner
University of California, Berkeley
Lorentz symmetry is one of the corner stones of modern physics. As such it should
not only hold for photons, but also for other particles such as the electron. Here we
search for violation of Lorentz symmetry by performing an analogue of a MichelsonMorley experiment for electrons. We split an electron-wavepacket bound inside
a calcium ion into two parts with different orientations. As the Earth rotates, the
absolute spatial orientation of the wavepackets changes and anisotropies in the
electron dispersion would modify the phase of the interference signal. To remove
noise, we prepare a pair of ions in a decoherence-free subspace, thereby rejecting
magnetic field fluctuations common to both ions. After a 23 hour measurement, we
limit the energy variations to 11 mHz, verifying the isotropy of the electron’s motion
at the 10−18 level, an improvement of up to two orders of magnitude over previous
work. Alternatively, we can interpret our result as testing the rotational invariance of
the Coulomb potential. Assuming Lorentz symmetry holds for electrons and that the
photon dispersion relation governs the Coulomb force, we obtain a fivefold improved
limit on anisotropies in the speed of light. Our experiment demonstrates the potential
of quantum information techniques in the search for physics beyond the Standard
Model.
ICOLS 2015, Singapore, June 28 - July 3, 2015
13
Ch.2. Invited Talk Abstracts
Tuesday, 9:00
Optical clocks with trapped ions
Ekkehard Peik
Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
Great progress has been made in the development of atomic clocks at optical frequencies and a number of different systems have recently been evaluated with systematic
uncertainties in the range of 10−18 (see [1] for a recent review). Comparisons of
frequencies and frequency ratios are now performed to affirm these evaluations, and
can also lead to improved tests of relativity and fundamental principles.
The 171 Yb+ ion provides two reference transitions that are suitable for the realization of optical clocks: the 2 S1/2 (F = 0) → 2 D3/2 (F = 2) electric quadrupole (E2)
transition and the 2 S1/2 (F = 0) → 2 F 7/2 (F = 3) electric octupole (E3) transition.
While the first allows us to precisely determine magnetic and electric fields as well
as to characterize residual motion of the single laser-cooled ion in the trap, the latter
is suitable as the reference in an optical clock with very small systematic uncertainty.
Furthermore, its natural linewidth in the nHz-range provides the potential for high
stability. To avoid the light shift associated with the excitation of the E3 transition,
we have implemented a generalized Ramsey excitation scheme. A measurement of
the static differential polarizability of the E3 transition with an uncertainty of less
than 2% based on light shift measurements with near-infrared lasers and improved
knowledge of the thermal radiation affecting the ion allow us to correct the blackbody
radiation shift with a fractional uncertainty of less than 2 × 10−18 , that is the second
largest contribution to the total systematic uncertainty of 3 × 10−18 .
A still lower sensitivity against frequency shifts from external fields can be
expected for the nuclear transition in 229 Th3+ at about 160 nm wavelength with a
linewidth in the mHz range [2]. A direct optical detection of the 229 Th isomer’s
excitation or decay is still missing. Our approach to achieve this goal is to use
two-photon laser excitation via electronic bridge processes in trapped 229 Th+ ions.
A high density of electronic states promises a strongly enhanced nuclear excitation
rate. Presently, the experimental search for laser excitation of the isomeric state is
ongoing.
References
[1] A. D. Ludlow, M. M. Boyd, J. Ye, E. Peik, P. O. Schmidt, arXiv:1407.3493 (Rev. Mod. Phys., in print)
[2] E. Peik, M. Okhapkin, arXiv:1502.07322 (Comptes Rendus Physique, in print)
14
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Tuesday, 9:45
Frequency ratios of Sr, Yb, and Hg based optical
lattice clocks and their applications
Hidetoshi Katori
Quantum Metrology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
Innovative Space-Time Project, ERATO, Japan Science and Technology Agency, Bunkyo-ku,
Tokyo 113-8656, Japan.
Department of Applied Physics, Graduate School of Engineering, The University of Tokyo,
Bunkyo-ku, Tokyo 113-8656, Japan.
We report on recent progress of optical lattice clocks with neutral strontium (87Sr),
ytterbium (171Yb) and mercury (199Hg) atoms. In particular, we present frequency
comparison between the clocks locally via an optical frequency comb and between
two Sr clocks at remote sites using a phase-stabilized fibre link. We first describe
cryogenic Sr optical lattice clocks [1] that reduce the room-temperature blackbody
radiation shift by two orders of magnitude and serve as a reference in the following
clock comparisons. Similar physical properties of Sr and Yb atoms, such as transition
wavelengths and vapour pressure, have allowed our development of a compatible
clock for both species. A cryogenic Yb clock is evaluated by referencing a Sr
clock. We also report on an Hg clock [2], which shows one order of magnitude
less sensitivity to blackbody radiation, while its large nuclear charge makes the
clock sensitive to the variation of fine-structure constant. Connecting all three types
of clocks by an optical frequency comb, the ratios of the clock frequencies are
determined with uncertainties smaller than possible through absolute frequency
measurements. Finally, we address a synchronous frequency comparison [3] between
two Sr-based remote clocks over a distance of 15 km between RIKEN and the
University of Tokyo, as a step towards relativistic geodesy.
References
[1] I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, H. Katori, Nature Photon. 9, 185-189 (2015).
[2] K. Yamanaka, N. Ohmae, I. Ushijima, M. Takamoto, H. Katori, arXiv:1503.07941.
[3] T. Akatsuka, H. Ono, K. Hayashida, K. Araki, M. Takamoto, T. Takano, H. Katori, Jpn. J. Appl. Phys.
53, 032801 (2014).
ICOLS 2015, Singapore, June 28 - July 3, 2015
15
Ch.2. Invited Talk Abstracts
Tuesday, 10:15
High accuracy atomic clock and its probe of quantum
many-body physics
Jun Ye
JILA, National Institute of Standards and Technology and University of Colorado, 440 UCB,
Boulder, CO 80309-0440, USA
Using a highly stable laser (1 × 10−16 stability from 1 to 1000 s) [1] to probe 2000
Sr atoms confined in a zero-differential ac Stark shift optical lattice, we achieve
optical atomic clock stability of 2.2 × 10−16 τ −1/2 versus averaging time τ. With
this stability, we have performed a new round of systematic evaluation of the JILA
Sr clock, improving many uncertainties that limited our previous measurements
[2]. For the lattice laser ac Stark uncertainty, we identify the operating optical
frequency where the scalar and tensor components of the shift cancel, allowing for
state-independent trapping with clock shifts at the 1 × 10−18 level. For the blackbody
radiation-induced frequency shift uncertainty, we control and monitor the atoms’
thermal environment using accurate radiation thermometry, which is traceable to the
NIST ITS-90 absolute temperature scale [3]. We also directly measure the component
of the strontium atomic structure that is responsible for the spectral response to roomtemperature BBR. We have thus reduced the total uncertainty of the JILA Sr clock
to 2.1 × 10−18 [4]. The clock precision has opened a new platform to explore a
strongly interacting spin system. Our collective spin measurements reveal signatures
of the development of many-body correlations during the dynamical evolution [5],
including non-equilibrium two-orbital SU(N) magnetism when we open the system
to as many as 10 nuclear spin sublevels [6].
References
[1] M. Bishof et al., ”Optical spectrum analyzer at the atomic quantum projection noise limit,” Phys. Rev.
Lett. 111, 093604 (2013).
[2] B. J. Bloom et al., ”An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506,
71-75 (2014).
[3] W. L. Tew et al.,”Calibration of thin-film platinum sensors for use in the JILA SrII Clock,” Natl Inst.
Stand. Technol. Intern. Rep. http://dx.doi.org/10.6028/NIST.IR.8046 (2015).
[4] T. L. Nicholson et al., ”Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,”
Nature Comm. 6, 6896/1-8 (2015).
[5] M. J. Martin et al., ”A quantum many-body spin system in an optical lattice clock,” Science 341,
632-636 (2013).
[6] X. Zhang et al., ”Spectroscopic observation of SU(N)-symmetric interactions in Sr orbital magnetism,”
Science 345, 1467-1473 (2014).
16
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Tuesday, 11:15
Quantum networks with optical frequency combs
Nicolas Treps
Laboratoire Kastler Brossel, UPMC - Sorbonne Universite, ENS, CNRS, Paris, France
Photonic architectures have emerged as a viable candidate for the development of
quantum information processing protocols. Photons are immune from environmental
disturbances, readily manipulated with classical tools, and subject to high efficiency
detection. While strong nonlinear interactions at the single photon level are difficult
to achieve, it is possible to initiate an interaction among photonic channels through
the act of measurement. Such measurement-induced nonlinearities are the basis of
linear optical quantum computing. We present here a scalable and on-demand way to
generate versatile multipartite quantum networks within one single beam. A 76MHz
train of 150fs optical pulses centered at 795nm is used to synchronously pump
an optical parametric oscillator (OPO) below threshold, generating co-propagating
multi-mode squeezing[1]. Frequency resolved homodyne detection is employed
to characterize the multipartite entanglement and a novel method is presented that
allows to verify multimode entanglement in any partition. Starting from a 10-partition
in the frequency domain, we demonstrate entanglement with respect to all 115974
possible K-partitions[2]. This highly entangled source can be turned into any type of
quantum network benefiting from the versatility of the measurement process[3]. This
procedure turns the source into a quantum network simulator, allowing in our case to
generate up to 12 mode cluster states and testing 5-players secret sharing. Finally,
combining multimode detection system and computer based post-processing one can
perform measurement based quantum computing operations[4]. The scalability of
the source and the versatility of the measurement process make it a very promising
candidate towards non-trivial multimode quantum information tasks.
Multimode quantum source
50/50 B.S.
e
Diod
y
Arra
MBQC
LINEAR
OPERATION
-
Figure 1: Scheme for Measurement Based Quantum Information
References
[1] J. Roslund, R. M. De Araujo, S. Jiang, and C. Fabre, Nature Photonics 8, 109 (2014).
[2] S. Gerke, J. Sperling, W. Vogel, Y. Cai, J. Roslund, N. Treps, and C. Fabre, Phys Rev Lett 114, 050501
(2015).
[3] G. Ferrini, J. P. Gazeau, T. Coudreau, C. Fabre, and N. Treps, New J Phys 15, 093015 (2013).
[4] G. Ferrini, J. Roslund, F. Arzani, Y. Cai, C. Fabre, and N. Treps, Phys Rev A 91, 032314 (2015).
ICOLS 2015, Singapore, June 28 - July 3, 2015
17
Ch.2. Invited Talk Abstracts
Tuesday, 11:45
Adaptive Quantum Optics and its Application:
Quantum-Secure Authentication
Pepijn Pinkse
Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of
Twente, PO Box 217, 7500 AE Enschede, The Netherlands
Disorder in optical media is usually considered a nuisance. Introducing “Adaptive
Quantum Optics”, we will show how, by exploiting disorder, photonic networks
can be built [1]. These networks consist e.g., of random photonic media in combination with wavefront modulators. Together they allow control of the path of
light through the disordered nanophotonic system. These disordered systems have
intriguing and unexpected applications: they can be used as “physical unclonable
function”, unclonable authentication keys that can be read out via Quantum-Secure
Authentication (QSA) [2]. QSA [See Fig. 1] is secure against copying of the key,
because it uses a key consisting of millions of randomly organized nanoparticles,
which is extremely difficult to copy due to technological limitations. QSA is secure
against digital emulation of the key because the small number of photons in the
challenge makes it impossible for an attacker to extract the spatial shape of the
challenge. Since the attacker cannot characterize the challenge, he cannot generate
the correct response by emulation. QSA provides authentication without relying on
stored secrets. Moreover, QSA does not involve unproven mathematical assumptions
and is relatively straightforward to implement.
Figure 1: a, Schematic of the Quantum-Secure Authentication setup, from [2]. A
spatial light modulator (SLM1) transforms a weak laser beam into a “challenge”
that contains more spatial degrees of freedom than photons. The optical multiplescattering key converts the challenge into a “response”. SLM2 is programmed
to convert the expected response into a plane wave. b, If the key is correct, the
few-photon response will be focused onto the detector. c, If the key is wrong, the
few-photon response will not be focused onto the detector.
References
[1] S. R. Huisman et al., Opt. Expr. 23, 3102 (2015).
[2] S. A. Goorden et al., Optica 1, 421 (2014).
18
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Tuesday, 14:45
Precision measurement of the Newtonian
gravitational constant by atom interferometry
Gabriele Rosi
Dipartimento di Fisica e Astronomia and LENS, Universita‘ di Firenze - INFN Sezione di
Firenze, Via Sansone 1, 50019 Sesto Fiorentino, Italy
The accurate determination of the Gravitational Constant G has always been a
challenging task [1]. After 300 different measurements, starting from the original one
performed by Cavendish in 1798 [2], the G value still now presents a large relative
uncertainty compared to all other physical constants. In order to detect systematic
effects that plague such measurements the use of different methods with respect to
the traditional ones is crucial. Here we report on the first precise determination of
G using microscopic test masses in free fall (cold Rubidium atoms) and quantum
interferometry to probe gravity [3]. We obtain the value G = 6.67191(99)x10−11 m3
kg−1 s−2 with a relative uncertainty of 150 ppm [4]. Our value is at 1.5 combined
standard deviations from the current recommended value of the Committee on Data
for Science and Technology (CODATA).
Figure 1
References
[1] T. Quinn, "Measuring big G", Nature 408, 919-921 (2000)
[2] H. Cavendish, "Experiments to determine the density of the Earth", Philosophical Transactions of the
Royal Society of London 88, 469-526 (1798)
[3] A. Peters et al., "Measurement of gravitational acceleration by dropping atoms" Nature 400, 849-852
(1999)
[4] G. Rosi et al., "Precision Measurement of the Newtonian Gravitational Constant Using Cold Atoms",
Nature 510, 518-521 (2014)
ICOLS 2015, Singapore, June 28 - July 3, 2015
19
Ch.2. Invited Talk Abstracts
Tuesday, 15:15
The generation and use of solitonic matter-waves in
atom optics
Nicholas Robins
Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Australian National
University, Canberra, 0200, Australia
In weakly nonlinear dispersive systems, solitons are spatially localized solutions
which propagate without changing shape through a delicate balance between dispersion and self-focusing nonlinear effects [1]. These states have been observed and
studied in Bose-Einstein condensates (BECs), where interatomic collisions give rise
to such nonlinearities [2].
As an introduction, the generation of bright solitonic matter waves in a degenerate
gas of rubidium-85 will be discussed, touching on the question of whether these
states are truly solitons with respect to theoretical definitions. The properties of
delta-kick cooled clouds [3] will be also be compared with solitonic matter-waves.
The first experimental realization of a solitonic atom interferometer will then be
presented [4]. A Bose-Einstein condensate of 104 atoms of 85 Rb is loaded into a
horizontal optical waveguide. Through the use of a Feshbach resonance, the s-wave
scattering length of the 85 Rb atoms is tuned to a small negative value. This attractive
atomic interaction then balances the inherent matter-wave dispersion, creating a bright
solitonic matter wave. A Mach-Zehnder interferometer is constructed by driving
Bragg transitions with the use of an optical lattice colinear with the waveguide.
Matter-wave propagation and interferometric fringe visibility are compared across a
range of s-wave scattering values including repulsive, attractive and noninteracting
values. The solitonic matter wave is found to significantly increase fringe visibility,
even compared with a noninteracting cloud.
A huge body of theoretical work exists on the collisions and interactions of
matter-wave solitons. It now seems feasible to begin systematically studying such
systems in the laboratory. Recent work on the study of excited state solitons will
be introduced and possible applications to precision atom interferometry will be
discussed.
References
[1] M.J. Ablowitz and P. A. Clarkson. Solitons, Nonlinear Evolution Equations and Inverse Scattering.
Cambridge University Press, (1991).
[2] F. Kh. Abdullaev, A. Gammal, A. M. Kamchatnov, and L. Tomio. Dynamics of bright matter wave
solitons in a Bose-Einstein condensate. International Journal of Modern Physics B, 19, 3415, (2005).
[3] G. D. McDonald, C. C. N. Kuhn, S. Bennetts, J. E. Debs,K. S. Hardman, M. Johnsson, J. D. Close,
and N. P. Robins, 80¯hk momentum separation with Bloch oscillations in an optically guided atom
interferometer, Phys. Rev. A 88, 053620 (2013).
[4] G. D. McDonald, C. C. N. Kuhn, K. S. Hardman, S. Bennetts, P. J. Everitt, P. A. Altin, J.E. Debs, J. D.
Close, N. P. Robins, A Bright Solitonic Matter-Wave Interferometer, Phys. Rev. Lett. 113, 013002 (2014)
20
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Wednesday, 9:00
From Many-Body Localization to Novel Rydberg
Quantum Magnets - New Frontiers for Ultracold
Quantum Gases
Immanuel Bloch
Max-Planck Institute of Quantum Optics, 85748 Garching, Germany
Ludwig-Maximilians University, 80799 Munich, Germany
Ever since the original proposal of Anderson localization, the question of whether
localization can be maintained in the presence of interactions has intrigued a generation of condensed matter physicists and led to heated discussions in the field. Most
recently, the question could be answered affirmatively by identifying a "many-body
localized" phase for interacting particles. The MBL phase is associated with the
breakdown of ergodicity, and thereby renders the most fundamental assumption of
statistical physics invalid. Furthermore, the MBL transition marks a new boundary
between the quantum world and our classical world that can be observed in a manybody setting. Our work makes use of advanced preparation and detection techniques
in the closed quantum systems of ultracold gases to unambiguously demonstrate the
MBL phase for the first time.
In the talk I will discuss preparation and detection techniques used to reveal this
hotly debated new many-body phase. In the second part of my talk, I will focus
on novel experiments realizing long-range interacting quantum magnets both in the
’frozen gas’ and ’Rydberg dressed’ regime. The latter offers remarkable possibilities
to engineer long-range interacting and long-lived dressed Rydberg atoms that open a
new avenue for exploring non-standard quantum magnetism as well as for realizing
supersolids.
ICOLS 2015, Singapore, June 28 - July 3, 2015
21
Ch.2. Invited Talk Abstracts
Wednesday, 9:45
Cold atomic gases in a flat box:
A new window on quantum many-body physics
Jean Dalibard
Collège de France and Laboratoire Kastler Brossel
Most experimental studies with quantum gases are performed with atoms confined
in a harmonic potential. This geometry is well suited for the investigation of some
aspects of equilibrium properties of the gas as well as specific collective modes. However the non-homogeneity of these gases prevents one from addressing an important
range of questions related to long-range correlations in the fluid. This restriction is
particularly significant for low dimensional systems, where these correlations may
evidence the emergence of novel phases of matter.
In this talk I will discuss some recent experimental investigations on uniform
Bose gases in box-like potentials [1,2]. With an emphasis on two-dimensional
systems, I will address both the equilibrium properties of the gas as well as some
aspects of non-equilibrium physics, which result from a quench cooling of the fluid
in direct relation with the celebrated Kibble-Zurek mechanism [2,3,4].
This research is support by ERC (UQUAM project) and ANR (Agafon project).
References
[1] A. L. Gaunt, T. F. Schmidutz, I. Gotlibovych, R. P. Smith, and Z. Hadzibabic, Phys. Rev. Lett., 110,
200406, (2013).
[2] L. Chomaz, L. Corman, T. Bienaimé, R. Desbuquois, C. Weitenberg, S. Nascimbène, J. Beugnon,
J. Dalibard, Nature Commun. 6, 6162, (2015).
[3] L. Corman, L. Chomaz, T. Bienaimé, R. Desbuquois, C. Weitenberg, S. Nascimbène, J. Dalibard, and
J. Beugnon, Phys. Rev. Lett., 113, 135302, (2014).
[4] N. Navon, A. L. Gaunt, R. P. Smith, Z. Hadzibabic, Science 347, 167, (2015).
22
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Wednesday, 10:15
New frontiers in quantum simulation enabled by
precision laser spectroscopy
Ana Maria Rey
JILA, NIST and University of Colorado, Boulder
Ultracold atomic systems have been proposed as ideal quantum simulators for condensed matter systems. Recent advances in cooling, trapping and manipulating
alkaline earth atoms –currently the basis of the most precise atomic clocks in the
world–, are opening new exciting opportunities for the exploration of a wider range
of many-body phenomena, even above quantum degeneracy. In this talk I will discuss
our recent progress at JILA on the use of Sr atoms as quantum simulators of iconic
Hamiltonians that fall under the general heading of quantum magnetism as well as
Hamiltonians without solid state analogs. I will discuss a particularly promising
direction towards the exploration of rich many-body physics at temperature regimes
above quantum degeneracy allowed by state-of-the-art laser precision spectroscopy.
In particular I will present our ideas of exploring p-wave interactions, SU(N) orbital
magnetism, and spin-orbit physics in an optical lattice clock by using the internal
degrees of freedom as synthetic dimensions.
ICOLS 2015, Singapore, June 28 - July 3, 2015
23
Ch.2. Invited Talk Abstracts
Wednesday, 11:15
Antiferromagnetism with Ultracold Atoms
Randall Hulet
Rice University, Department of Physics and Astronomy
Ultracold atoms on optical lattices form a versatile platform for studying manybody physics, with the potential of addressing some of the most important issues in
strongly correlated matter. Progress, however, has been stymied by an inability to
cool to sufficiently low temperatures. In this talk, I will present our experimental
results on the characterization of the three-dimensional Hubbard model near halffilling, realized using two spin-states of fermionic atomic lithium (6 Li). We have
developed a compensated optical lattice that has enabled, for the first time, the
achievement of temperatures that are below the tunneling energy in the lattice, t. For
strong interactions we observe the emergence of a density plateau and a reduction
of the compressibility, indicative of the formation of a Mott insulator [1]. The
Hubbard model is known to exhibit antiferromagnetism at temperatures below the
Néel temperature TN . We have detected antiferromagnetic correlations by spinsensitive Bragg scattering of light [2]. With improved cooling, it may be possible
to resolve the open question of whether the Hubbard model contains the necessary
ingredients to describe high-temperature superconductivity.
References
[1] P. M. Duarte et al., Phys. Rev. Lett. 114, 070403 (2015).
[2] R. A. Hart, P. M. Duarte et al., Nature 519, 211 (2015).
24
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Wednesday, 11:45
Quantum walks with neutral atoms
Andrea Alberti
Institut für Angewandte Physik, Wegelerstr. 8, 53115 Bonn, Germany
The discrete-time quantum walk is a prime example of quantum transport: a spin1/2 particle is delocalised over a very large Hilbert space through discrete steps in
space and time. The quantum diffusion of the particle is strongly dominated by the
underlying spin-orbit coupling, which strongly correlates position and spin degrees of
freedom. We experimentally investigate this type of quantum motion using ultracold
atoms in spin-dependent optical lattices. Atoms in spin-up and spin-down states are
transported by two fully independent optical lattices, which we actively stabilize
with respect to each other to a precision of λ /5000.
Quantum walks allows the observation of different textbook transport phenomena
like Bloch oscillations, Landau-Zener tunnelling, and Zitterbewegung motion. Besides these classic examples, quantum transport dynamics is made far richer by time
discreteness — an inherent property of the walks: quantum resonance phenomena
occur depending on the rational or irrational character of an external artificial field
applied to the atoms [1].
Physical insight into the “quantumness” of the walk is given by interaction-free
measurements of the atom’s position, which allow us to strictly rule out any physical
interpretation of the experiments based on classical, well-defined trajectories [2].
Our experiment demonstrates a 6σ violation of the Leggett-Garg inequality, proving
the nonclassicality of the motion of a single atom — the most massive object that
has been so far tested by a Leggett-Garg falsification experiment.
The realisation of spin-orbit coupling in two-dimensional lattices gives us the
possibility to explore in the near future the rich topological structure of quantum
walks through direct transport phenomena.
References
[1] M. Genske, W. Alt, A. Steffen, A. H. Werner, R. F. Werner, D. Meschede, A. Alberti, Electric
quantum walks with individual atoms, Phys. Rev. Lett. 110, 190601 (2013); C. Cedzich, T. Rybár,
A. H. Werner, A. Alberti, M. Genske and R. F. Werner, Propagation of quantum walks in electric fields,
Phys. Rev. Lett. 111, 160601 (2013).
[2] C. Robens, W. Alt, D. Meschede, C. Emary, and A. Alberti, Ideal Negative Measurements in Quantum
Walks Disprove Theories Based on Classical Trajectories, Phys. Rev. X 5, 011003 (2015).
ICOLS 2015, Singapore, June 28 - July 3, 2015
25
Thursday, 9:00
Ch.2. Invited Talk Abstracts
Spectroscopy of muonic atoms and the proton radius
puzzle
Aldo Antognini for the CREMA collaboration
Institute for Particle Physics, ETH, 8093 Zurich, Switzerland
Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
Muonic atoms are atomic bound states of a negative muon and a nucleus. The muon,
which is the 200 times heavier cousin of the electron, orbits the nucleus with a 200
times smaller Bohr radius. This enhances the sensitivity of the atomic energy levels
to the nuclear structure tremendously.
By performing laser spectroscopy of the 2S − 2P transitions in muonic hydrogen
we have determined the proton root mean square charge radius r p = 0.84087(39) fm
[1,2], 20 times more precisely than previously obtained. Yet, this value disagrees by
4 standard deviations from the value extracted from “regular” hydrogen spectroscopy
and also by 6 standard deviations from electron-proton scattering data.
The variance of the various proton radius values has led to a very lively discussion
[3] in various fields of physics: particle and nuclear physics (proton structure, new
physics, scattering analysis), in atomic physics (hydrogen energy level theory, fundamental constants) and fundamental theories (bound-state problems, QED, effective
field theories). At present, however, the resolution to the problem remains unknown.
An important piece of information regarding the “proton radius puzzle” is provided by spectroscopy of muonic deuterium and muonic helium (µ 4 He+ , µ 3 He+ )
ions [4]. We present preliminary results of muonic deuterium and helium spectroscopy, which beside helping to disentangle the origin of the observed “proton
radius puzzle” also provide values of the corresponding nuclear charge radii with
relative accuracies of few 10−4 to be compared with precise values already available
from electron-proton scattering [5]. Moreover absolute radii of 6 He and 8 He halo
nuclei can be obtained when our measurements in muonic helium are combined with
the corresponding isotopic shift measurements [6]. These nuclear radii represent
precision benchmarks for few-nucleon ab-initio nuclear theories and enable enhanced
bound-state QED tests for one- and two-electron systems when combined with XUV
frequency comb based measurements planned in “regular” He+ [7] and He [8].
References
[1] R. Pohl et al., Nature 466, 213 (2010).
[2] A. Antognini et al., Science 339, 417 (2013).
[3] R. Pohl, R. Gilman, G.A. Miller, K. Pachucki, Annu. Rev. Nucl. Part. Sci 63, 165 (2013).
[4] A. Antognini et al., Can. J. Phys. 89, 47 (2011).
[5] I. Sick, Phys Rev C 77, 941392(R) (2008).
[6] Z.T. Lu, P. Mueller, G.W.F. Drake et al., Rev. Mod. Phys. 85, 1383 (2013).
[7] M. Herrmann et al., Phys. Rev. A 79, 052505 (2009).
[8] D.Z. Kandula et al., Phys. Rev. A 84, 062512 (2011).
26
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Thursday, 9:45
Helium n=2 triplet P fine structure,
quantum-mechanical interference shifts, and
frequency-offset separated oscillatory fields
Eric Hessels
York University
Because of its long lifetime (98 ns) and its large fine structure (32 GHz), the 23 P
states of helium have long been considered a good system for determining the finestructure constant. The status of this program of increasingly accurate experiments
[1-5] and theory [6] is reviewed.
Quantum-mechanical interference [7] is found to influence the measurements of
the 23 P fine structure. Even when off-resonant transitions are separated by over a
thousand natural widths from the resonance being measured, the interference causes
significant shifts in the measured line centers. Similar shifts are expected to be
important for a wide range of precision measurements.
We are preforming higher-precision measurements of the 23 P fine structure
using a new frequency-offset separated-oscillatory-field (FOSOF) technique. The
FOSOF technique uses two oscillating fields, with one field offset in frequency from
the other. As a result, the relative phase of the two fields oscillates at the offset
frequency. The new technique shows advantages for reducing systematic effects in
separated-oscillatory field measurements.
References
[1] M.C. George, L.D. Lombardi, and E.A. Hessels, Phys. Rev. Lett., 87, 173002 (2001); J.S. Borbely,
M.C. George, L.D. Lombardi, M. Weel, D.W. Fitzakerley, and E.A. Hessels, Phys. Rev. A, 79, 060503
(2009).
[2] F. Minardi, G. Bianchini, P.C. Pastor, G. Giusfredi, F.S. Pavone, and M. Inguscio, Phys. Rev. Lett., 82,
1112 (1999).
[3] J. Castillega, D. Livingston, A. Sanders, and D. Shiner, Phys. Rev. Lett., 84, 4321 (2000); M. Smiciklas
and D. Shiner, Phys. Rev. Lett., 105, 123001 (2010).
[4] G.-P. Feng, X. Zheng, and S.-M. Hu, Phys. Rev. A, 91, 030502 (2015).
[5] T. Zelevinsky, D. Farkas, and G. Gabrielse, Phys. Rev. Lett., 95, 203001 (2005).
[6] K. Pachucki and V. A. Yerokhin, Phys. Rev. Lett., 104, 070403 (2010).
[7] A. Marsman, M. Horbatsch, and E.A. Hessels, Phys. Rev. A, 86, 012510 (2012); A. Marsman, M.
Horbatsch, and E.A. Hessels, Phys. Rev. A, 86, 040501 (2012); A. Marsman, E.A. Hessels, and M.
Horbatsch, Phys. Rev. A, 89, 043403 (2014).
ICOLS 2015, Singapore, June 28 - July 3, 2015
27
Ch.2. Invited Talk Abstracts
Thursday, 10:15
The Boltzmann constant from the shape of a
molecular vibration-rotation transition
Livio Gianfrani
Dipartimento di Matematica e Fisica, Seconda Università di Napoli, Caserta, Italy
The expression of the Doppler width of a spectral line, valid for a gaseous sample at
the thermodynamic equilibrium, represents a powerful tool to link the thermodynamic
temperature to an absolute frequency and a frequency interval. This is the basis of a
relatively new method of primary gas thermometry, known as Doppler Broadening
Thermometry (DBT), which is currently at the stage of further development and
optimization in a few labs worldwide. I will report on ongoing efforts at University
of Naples 2 towards the development of low-uncertainty DBT, using precision
molecular spectroscopy in the near-infrared region, for the aims of the spectroscopic
determination of the Boltzmann constant and new definition of the unit kelvin. In
the 3rd -generation experiment, the goal is to further reduce the global uncertainty
as compared to previous determinations [1, 2], thus approaching the target accuracy
of one part in 106 . The molecules of interest are H2 18 O and C2 H2 , both showing
relatively strong absorption features at the wavelength of 1.39 µm. Main progresses
and current limitations will be highlighted, with a special focus to the line shape
problem. Furthermore, a revised uncertainty budget will be presented and discussed.
In this respect, it will be shown that the achievement of the part-per-million level
is a realistic possibility for the DBT method, thus making it competitive with more
consolidated approaches, namely, Acoustic Gas Thermometry (AGT) and Dielectric
Constant Gas Thermometry (DCGT).
References
[1] G. Casa, A. Castrillo, G. Galzerano, R. Wehr, A. Merlone, D. Di Serafino, P. Laporta, and L. Gianfrani,
Phys. Rev. Lett., 100, 200801, (2008).
[2] L. Moretti, A. Castrillo, E. Fasci, M. D. De Vizia, G. Casa, G. Galzerano, A. Merlone, P. Laporta, and
L. Gianfrani, Phys. Rev. Lett, 111, 060803, (2013).
28
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Thursday, 11:15
Chiral interaction of light and matter in confined
geometries
Arno Rauschenbeutel
Vienna Center for Quantum Science and Technology, Institute of Atomic and Subatomic
Physics, Vienna University of Technology, Stadionallee 2, 1020 Wien, Austria
When light is strongly transversally confined, significant local polarization components that point in the direction of propagation arise. In contrast to paraxial light
fields, the corresponding intrinsic angular momentum of the light field is positiondependent—an effect referred to as spin–orbit interaction of light. Remarkably, the
light’s spin can even be perpendicular to the propagation direction. The interaction of
emitters with such light fields leads to new and surprising effects. For example, when
coupling gold nanoparticles or atoms to the evanescent field surrounding a silica
nanophotonic waveguide, the intrinsic mirror symmetry of the particles’ emission
is broken. This allowed us to realize chiral nanophotonic interfaces in which the
emission direction of light into the waveguide is controlled by the polarization of the
excitation light [1] or by the internal state of the atoms [2], respectively. Moreover,
we employed this chiral interaction to demonstrate nonreciprocal transmission of
light at the single-photon level through a silica nanofiber [3]. The resulting optical
diode is the first example of a new class of nonreciprocal nanophotonic devices which
exploit the chiral interaction between quantum emitters and transversally confined
photons.
References
[1] J. Petersen, J. Volz, and A. Rauschenbeutel, Science 346, 67 (2014).
[2] R. Mitsch, C. Sayrin, B. Albrecht, P. Schneeweiss, and A. Rauschenbeutel, Nature Commun. 5, 5713
(2014).
[3] C. Sayrin, C. Junge, R. Mitsch, B. Albrecht, D. O’Shea, P. Schneeweiss, J. Volz, and A. Rauschenbeutel, arXiv:1502.01549.
ICOLS 2015, Singapore, June 28 - July 3, 2015
29
Ch.2. Invited Talk Abstracts
Thursday, 11:45
Coherence of a Bose-Einstein Condensed Light Field
Martin Weitz
Institut f"ur Angewandte Physik, Universit"at Bonn, Wegelerstr. 8, 53115 Bonn, Germany
Bose-Einstein condensation has been observed with cold atomic gases, quasiparticles
in solid state systems as polaritons, and more recently also with photons in a dyefilled optical microcavity [1]. I will here describe measurements of our Bonn group
determining both the first and the second order coherence of a photon Bose-Einstein
condensate. The optical condensate is generated in a wavelength-sized optical cavity,
where the small mirror spacing imprints a low-frequency cutoff with a spectrum of
photon energies restricted to well above the thermal energy. Thermal equilibrium
of the photon gas is achieved by repeated absorption re-emission cycles in dye
molecules [2]. In this system the photo-excitable dye molecules act as a reservoir for
the condensate particles, which allows to reach a regime with large "grand canonical"
number fluctuations, of order of the total particle number [3]. The measured second
order coherence correspondingly vanishes, as in a thermal (lamp-type) source. To
study the first order coherence of the condensate, we have examined the temporal
interference signal of the photon Bose-Einstein condensate with a narrowband laser
source acting as a phase reference [4]. The intensity fluctuations of the grand
canonical statistics condensate lead to phase jumps in the observed interference
signal, with a rate reducing for larger condensate sizes with respect to the system size.
Our experimental data reveals a regime that is phase coherent despite the absence
of the second order coherence. Grand-canonical statistics optical sources in the
condensed phase hold prospects for both fundamental studies and optical imaging
technology.
References
[1] See, e.g.: Novel superfluids, Vol. 1, K. H. Bennemann and J. B. Ketterson (eds.) (Oxford University
Press, Oxford, 2013).
[2] J. Klaers, J. Schmitt, F. Vewinger, and M. Weitz, Nature 468, 545 (2010).
[3] J. Schmitt, T. Damm, D. Dung, F. Vewinger, J. Klaers, and M. Weitz, Phys. Rev. Lett. 112, 030401
(2014).
[4] J. Schmitt et al., in preparation.
30
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Thursday, 14:00
High Harmonic Spectroscopy of Molecules
Chang Hee Nam
Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712,
Korea
Dept of Physics and Photon Science, GIST, Gwangju 500-712, Korea
High-harmonic radiation emitted from molecules in a strong laser field contains
the information on molecular structure and dynamics. When multiple molecular
orbitals are exposed to a strong laser field, the highest-occupied molecular orbital
(HOMO) is mostly ionized and thus emits strong high-harmonic radiation containing
the characteristics of HOMO. The radiation from the energetically lower-lying
molecular orbital (HOMO-1) is often too weak in investigating the characteristics
of the HOMO-1, necessitating special techniques to observe the radiation from the
HOMO-1. In the case of N2 molecules the multi-orbital effect could be observed
from the characteristics of high harmonics by applying femtosecond laser pulses to
aligned N2 molecules. As a more general approach, we showed that two-dimensional
high-harmonic spectroscopy could resolve high-harmonic radiation emitted from
the two highest-occupied molecular orbitals, HOMO and HOMO-1, of aligned
molecules. By applying an orthogonally polarized two-color laser field consisting
of the fundamental and its second harmonic fields, the characteristics attributed to
the two orbitals of CO2 molecules were found to be separately imprinted in odd and
even harmonics [1]. Two-dimensional high-harmonic spectroscopy could thus reveal
the multi-orbital characteristics of molecules, opening a new route to investigate
ultrafast molecular dynamics.
References
[1] H. Yun, K.-M. Lee, J. H. Sung, K. T. Kim, H. T. Kim, and C. H. Nam, Resolving multiple molecular
orbitals using two-dimensional high-harmonic spectroscopy, Phys. Rev. Lett. 114, 153901 (2015).
ICOLS 2015, Singapore, June 28 - July 3, 2015
31
Ch.2. Invited Talk Abstracts
Thursday, 14:45
Laser-induced filaments in the mid-infrared
Aleksei Zheltikov
Moscow State University
Texas A&M University
Russian Quantum Center
Laser-induced filamentation is a thrilling phenomenon of ultrafast optical physics,
in which diffraction of a laser beam is suppressed by a combined effect of selffocusing and transverse electron density profile induced by ultrafast photoionization.
While filamentation of ultrashort light pulses with peak powers above the selffocusing threshold is a universal phenomenon, observed in gases, liquids, and solids,
laser filaments in the atmosphere are of special significance as they offer unique
opportunities for long-range signal transmission, delivery of high-power laser beams,
and remote sensing of the atmosphere. With the critical power of self-focusing
scaling as the laser wavelength squared, the quest for longer-wavelength drivers,
which would radically increase the peak power and, hence, the laser energy in a
single filament, has been ongoing over two decades, during which time the available
laser sources limited filamentation experiments in the atmosphere to the near-infrared
and visible ranges. Here, we demonstrate filamentation of ultrashort mid-infrared
pulses in the atmosphere for the first time. We show that, with the spectrum of
a femtosecond laser driver centered at 3.9 micrometers, right at the edge of the
atmospheric transmission window, radiation energies above 20 mJ and peak powers
in excess of 200 GW can be transmitted through the atmosphere in a single filament.
Our studies reveal unique properties of mid-infrared filaments, where the generation
of powerful mid-infrared supercontinuum is accompanied by unusual scenarios
of optical harmonic generation, giving rise to remarkably broad radiation spectra,
stretching from the visible to the mid-infrared.
32
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Thursday, 15:15
Light-Neuron interactions: Key to understanding the
brain
Vincent Daria
Eccles Institute of Neuroscience, JCSMR, Australian National University, Canberra, Australia
In this talk, I will describe our efforts to use light to understand information processing in the brain. I will start with an established tool of using light for 3D brain
imaging via multi-photon microscopy, where within fundamental optical limits, provides a good spatial range for studying single neurons up to interconnected neurons
in a circuit. Within this spatial range, I will then talk about using patterned light to
photo-induce synaptic inputs and analyze how the spatio-temporal organization of
these inputs cause the neuron to fire an output. We use a dynamically programmable
hologram to produce 3D light patterns that can induce targeted and highly localized
synaptic inputs along the dendritic tree of a neuron. Such technique can also be
used for light-based recording of responses from multiple neurons - leading to an
all-optical method for stimulating and recording neuronal activity. To target neurons
deep within the brain tissue, the hologram can be added with an adaptive phasepattern to correct for optical aberrations caused by the brain tissue. Towards the
end, I will discuss preliminary results on using non-linear light-tissue interactions
to dynamically prune the neuron’s dendritic tree. The neuron’s output and overall
function in a neuronal circuit are said to be dependent on the spatial extent of its
dendritic tree. Hence, laser dendrotomy allows us to study morphology-dependent
neuronal function. These experiments are among many light-neuron interactions that
facilitate our understanding of how the brain works.
ICOLS 2015, Singapore, June 28 - July 3, 2015
33
Ch.2. Invited Talk Abstracts
Thursday, 16:15
Subradiant molecular lattice clock
Tanya Zelevinsky
Columbia University, USA
When diatomic molecules are trapped in an optical lattice, their quantum states
can be precisely controlled [1,2]. This leads to possibilities for ultrahigh-precision
spectroscopy, in analogy to atomic lattice clocks, but with the clock frequency based
on either electronic or vibrational dynamics [3]. Molecular clocks can thus probe
different physics than atomic clocks. We discuss the observation of deep subradiance
in ultracold strontium dimers, where the natural lifetimes are extended by up to 300fold [4]. The subradiance, ensured by quantum-mechanical symmetrization of the
molecular wave function, allows extremely high-resolution spectroscopy of weakly
bound molecules near the atomic intercombination-line asymptote. We confirm the
prediction of the radiative linewidths scaling as the molecular bond length squared [5].
We also measure and explain the asymptotic scaling of nonradiative molecular decay,
or predissociation. Furthermore, the weakly bound molecules have unexpectedly
large magnetic susceptibilities [6], and their forbidden transition strengths can be
tuned over many orders of magnitude with weak magnetic fields [7], opening doors
to even higher-resolution molecular clocks. Finally, we discuss other applications of
this lattice clock to molecular and fundamental physics.
References
[1] M. McDonald et al., Phys. Rev. Lett. 114, 023001 (2015).
[2] G. Reinaudi et al., Phys. Rev. Lett. 109, 115303 (2012).
[3] B. H. McGuyer et al., arXiv:1501.01236.
[4] B. H. McGuyer et al., Nat. Phys. 11, 32 (2015).
[5] B. Bussery-Honvault and R. Moszynski, Mol. Phys. 104, 2387 (2006).
[6] B. H. McGuyer et al., Phys. Rev. Lett. 111, 243003 (2013).
[7] B. H. McGuyer et al., arXiv:1503.05946.
34
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Thursday, 16:40
Improved Magneto-optical Trapping of a Diatomic
Molecule
Daniel McCarron
Yale University
The magneto-optical trap (MOT) is the workhorse technique for atomic physics in
the ultracold regime, serving as the starting point in applications from optical clocks
to quantum-degenerate gases. Recently, our group realized the first magneto-optical
trap for a molecule, strontium monofluoride (SrF) [1]. Here, we present results using
two alternative trapping schemes which improve upon the original work. In the first
[2], recent insights into the origin of the restoring force in type-II MOTs [3] (rarely
used for atoms but requisite for SrF and other candidate molecules) led to a simple
change in polarization scheme for the MOT lasers. In the second, states dark to the
restoring MOT beams are diabatically transferred to bright states by synchronously
reversing the magnetic field gradient and the laser polarization at RF frequencies.
For each scheme, the SrF MOT is loaded from a cryogenic buffer-gas beam slowed
by laser radiation pressure while images of laser-induced fluorescence allow us to
characterize each trap’s properties. Although magneto-optical trapping of diatomic
molecules is in its infancy, our results indicate that access to the ultracold regime may
be possible for several molecular species, with potential applications from quantum
simulation to ultracold chemistry to tests of fundamental symmetries.
References
[1] J. F. Barry, D. J. McCarron, E. B. Norrgard, M. H. Steinecker, D. DeMille, Nature 512, 286 (2014).
[2] D. J. McCarron, E. B. Norrgard, M. H. Steinecker, D. DeMille, New J. Phys. 17, 035014 (2015).
[3] M. R. Tarbutt, New J. Phys. 17, 015007 (2015).
ICOLS 2015, Singapore, June 28 - July 3, 2015
35
Ch.2. Invited Talk Abstracts
Thursday, 17:05
Atomic Hong-Ou-Mandel Experiment
Marc Cheneau
Laboratoire Charles Fabry – Institut d’optique
The celebrated Hong, Ou and Mandel (HOM) effect is one of the simplest illustrations
of two-particle interference, and is unique to the quantum realm. In the original
experiment, two indistinguishable photons arriving simultaneously in the input
channels of a beam-splitter were observed to always emerge together in one of the
output channels, in sharp contrast with the behaviour of distinguishable photons. In
this communication, we will report on the recent realisation of a closely analogous
experiment performed on atoms instead of photons [1]. This opens the prospect of
testing Bell’s inequalities involving mechanical observables of massive particles,
such as momentum, using methods inspired by quantum optics, with an eye on
theories of the quantum-to-classical transition. Our work also demonstrates a new
way to produce and benchmark twin-atom pairs that may be of interest for quantum
information processing and quantum simulation.
References
[1] R. Lopes et al., Nature 520, 66-68 (2015)
36
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Friday, 9:00
Quantum Nonlinear Optics for Quantum Science
Gerhard Rempe
Max Planck Institute of Quantum Optics, Hans Kopfermann Str. 1, 85748 Garching, Germany
Classical nonlinear optics is traditionally performed in a regime where light pulses
consist of many photons and media are made of many atoms so that one particle
more or less does not make a difference. Quantum nonlinear optics with few photons
requires media where one photon is enough to change the optical properties of the
medium. As one photon can be absorbed by not more than one (effective) atom,
this one atom must have a big effect on the medium. In an ensemble of atoms, such
scenario can be realized by combining the effects of slow light and Rydberg blockade,
thus replacing the vanishingly small photon-photon interaction by a large atom-atom
interaction. This scenario can be contrasted to a cavity quantum electrodynamics
scenario where just one atom is strongly coupled to an optical resonator, and where
the optical nonlinearity is large due to the spatial compression of the light quantum
inside a photonic box. The talk will discuss both scenarios and highlight recent
achievements, ranging from the nondestructive detection of an optical photon [1] and
its application for hybrid quantum gates [2] and heralded quantum memories [3] to
the realization of a single-photon switch [4] and transistor [5].
References
[1] A. Reiserer et al., Science 342, 1349 (2013).
[2] A. Reiserer et al., Nature 508, 237 (2014).
[3] N. Kalb et al., arXiv:1503.06709.
[4] S. Baur et al., PRL 112, 073901 (2014).
[5] D. Tiarks et al., PRL 113, 053602 (2014).
ICOLS 2015, Singapore, June 28 - July 3, 2015
37
Ch.2. Invited Talk Abstracts
Friday, 9:45
Quantum engineering and metrology with
Fiber Fabry-Perot microcavities
Jakob Reichel
Laboratoire Kastler Brossel, ENS / CNRS / UPMC / Collège de France
High-fidelity control over light-matter coupling plays a prominent role in all quantum
technologies, spurring the development of ingenious microcavity designs. Among
those, Fiber Fabry-Perot (FFP) microcavities are now being used by more than a
dozen research groups with at least six different quantum emitters, ranging from
neutral atoms and ions to quantum dots and diamond NV centers. In our experiments
with neutral atomic ensembles, we have used quantum Zeno dynamics [1] and
quantum feedback [2] to generate non-gaussian multiparticle entangled states in
ensembles of ∼ 40 atoms. In these experiments, the microcavity acts twice: first, as
a non-destructive atomic state detector which enables the entanglement generation.
Second, the cavity allows us to perform quantum state tomography with singleparticle resolution.
Cavity interaction also enables the generation of spin-squeezed states in much
larger ensembles [3]. Existing experiments, however, have not yet tested the gain
of spin squeezing at a metrologically relevant level. Doing so would be particularly
interesting for trapped-atom clocks: in these clocks, increasing the atom number is
not an option, so that there is no easy way to improve the clock stability once the
projection noise limit has been reached. This is the case of optical lattice clocks, but
also of compact clocks such as the Trapped-Atom Clock on a Chip (TACC) which
we have developed in collaboration with SYRTE (Observatoire de Paris). This clock
now has now reached an Allan variance of 5.8 × 10−13 in 1 s [4]. Recent progress in
FFP microcavity technology paves the way to spin squeezing in this clock.
References
[1] F. Haas, J. Volz, R. Gehr, J. Estève & J. Reichel, Science 344, 180 (2014).
[2] J. Volz, R. Gehr, G. Dubois, J. Estève & J. Reichel, Nature 475, 210 (2011).
[3] I. D. Leroux, M. H. Schleier-Smith & V. Vuletic, Phys. Rev. Lett. 104, 250801 (2010).
[4] R. Szmuk, V. Dugrain, W. Maineult, J. Reichel & P. Rosenbusch, arXiv:1502.03864 (2015).
38
ICOLS 2015, Singapore, June 28 - July 3, 2015
Ch.2. Invited Talk Abstracts
Friday, 11:45
Engineering Frequency-Time Quantum Correlation
of Narrow-Band Biphotons from Cold Atoms
Yoon-Ho Kim
Department of Physics, Pohang University of Science and Technology (POSTECH), Korea
The nonclassical photon pair, generated via a parametric process, is naturally endowed with a specific form of frequency-time quantum correlations. Here, we
report complete control of frequency-time quantum correlations of narrow-band
biphotons generated via spontaneous four-wave mixing in a cold atomic ensemble. We have experimentally confirmed the generation of frequency-anticorrelated,
frequency-correlated, and frequency-uncorrelated narrow-band biphoton states, as
well as verifying the strong nonclassicality of the correlations. Our work opens up
new possibilities for engineering narrow-band entangled photons for various quantum
information applications, such as, quantum networks and quantum repeaters.
References
[1] Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, Phys. Rev. Lett. 113, 063602 (2014).
ICOLS 2015, Singapore, June 28 - July 3, 2015
39
Friday, 11:45
Ch.2. Invited Talk Abstracts
Figure 1: The data show time-correlated, time-uncorrelated, and time-anticorrelated
joint temporal intensity functions of entangled biphoton states. (a) (d): experimental
joint temporal intensity function. (e) (h): theoretical joint temporal intensity function.
Arrows indicate biphoton optical precursors having positive time correlation.
40
ICOLS 2015, Singapore, June 28 - July 3, 2015
Author Index
A
N
Alberti, Andrea . . . . . . . . . . . . . . . . . . . . 25
Antognini, Aldo . . . . . . . . . . . . . . . . . . . 26
Nam, Chang Hee . . . . . . . . . . . . . . . . . . . 31
B
Peik, Ekkehard . . . . . . . . . . . . . . . . . . . . 14
Pinkse, Pepijn . . . . . . . . . . . . . . . . . . . . . 18
Bloch, Immanuel . . . . . . . . . . . . . . . . . . . 21
Budker, Dmitry . . . . . . . . . . . . . . . . . . . . 11
C
Cheneau, Marc . . . . . . . . . . . . . . . . . . . . 36
CREMA collaboration . . . . . . . . . . . . . . 26
D
Dalibard, Jean . . . . . . . . . . . . . . . . . . . . . 22
Daria, Vincent . . . . . . . . . . . . . . . . . . . . . 33
G
Gianfrani, Livio . . . . . . . . . . . . . . . . . . . . 28
H
Haeffner, Hartmut . . . . . . . . . . . . . . . . . . 13
Hessels, Eric . . . . . . . . . . . . . . . . . . . . . . .27
Hulet, Randall . . . . . . . . . . . . . . . . . . . . . 24
K
P
R
Rauschenbeutel, Arno . . . . . . . . . . . . . . 29
Reichel, Jakob . . . . . . . . . . . . . . . . . . . . . 38
Rempe, Gerhard . . . . . . . . . . . . . . . . . . . 37
Rey, Ana Maria . . . . . . . . . . . . . . . . . . . . 23
Robins, Nicholas . . . . . . . . . . . . . . . . . . . 20
Rosi, Gabriele . . . . . . . . . . . . . . . . . . . . . 19
S
Safronova, Marianna . . . . . . . . . . . . . . . 12
Schaetz, Tobias . . . . . . . . . . . . . . . . . . . . . 9
T
Thompson, Richard . . . . . . . . . . . . . . . . . 8
Treps, Nicolas . . . . . . . . . . . . . . . . . . . . . 17
W
Weitz, Martin . . . . . . . . . . . . . . . . . . . . . . 30
Y
Katori, Hidetoshi . . . . . . . . . . . . . . . . . . 15
Kim, Yoon-Ho . . . . . . . . . . . . . . . . . . . . . 39
Ye, Jun . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
M
Z
Matsukevich, Dzmitry . . . . . . . . . . . . . . 10
McCarron, Daniel . . . . . . . . . . . . . . . . . . 35
Zelevinsky, Tanya . . . . . . . . . . . . . . . . . . 34
Zheltikov, Aleksei . . . . . . . . . . . . . . . . . . 32
41
42