Seminar Schedule
Find upcoming seminars below. All talks are also
announced via
our mailing list and are also available via
a google
calendar (ical). Previous talks as well as a copy of
the slides will be made available for the foreseeable future
on the VIDEOS
page.
Thu 2021-04-15 17:00 CEST
Quantum Science Seminar #44: Quantum Computing
Dietrich Leibfried
National Institute of Standards and Technology
Boulder — Colorado — U.S.A.
Quantum Logic Control of a Single Molecular Ion
An amazing level of quantum control is routinely reached in
modern experiments with atoms, but similar control over
molecules has been an elusive goal. A method based on quantum
logic spectroscopy [1] can address this challenge for a wide
class of molecular ions [2,3]. We have now realized the basic
elements of this proposal. In our demonstration, we trap a
calcium ion together with a calcium hydride ion (CaH+) that is a
convenient stand-in for more general molecular ions. We
laser-cool the two-ion crystal to its motional ground state and
then drive Raman-transitions in the molecular ion, where a
transition in the molecule also deposits a single quantum of
excitation in the motion of the ion pair (motional
"sidebands"). We can efficiently detect this single
quantum of excitation with the calcium ion, which projects the
molecule into the final state of the sideband transition, a
known, pure quantum state. The molecule can be coherently
manipulated after the projection, and its resulting state read
out by another quantum logic state detection. We demonstrate
this by driving Rabi oscillations between different rotational
states [4, 5] and by entangling the molecular ion with the logic
ion [6]. All transitions in the molecule are either driven by a
single, far off-resonant continuous-wave laser or by a
far-off-resonant frequency comb. This makes the approach
suitable for quantum control and precision measurement of a
large class of molecular ions.
References
-
P.O. Schmidt, T. Rosenband, C. Langer, W. M. Itano, J. C. Bergquist, and D. J. Wineland
Spectroscopy using quantum logic
Science
309
749
2005
-
S. Ding and D. N. Matsukevich
Quantum logic for the control and manipulation of molecular ions using a frequency comb
New Journal of Physics
14
023028
2012
-
D. Leibfried
Quantum state preparation and control of single molecular ions
New Journal of Physics
14
023029
2012
-
C.-w. Chou, Ch. Kurz, D. B. Hume, P. N. Plessow, D. R. Leibrandt, and D. Leibfried
Preparation and coherent manipulation of pure quantum states of a single molecular ion
Nature
545
203
2017
-
C. W. Chou, A. L. Collopy, C. Kurz, Y. Lin, M. E. Harding, P. N. Plessow, T. Fortier, S. Diddams, D. Leibfried, and D. R. Leibrandt
Frequency-comb spectroscopy on pure quantum states of a single molecular ion
Science
367
1458
2020
-
Yiheng Lin, David R. Leibrandt, Dietrich Leibfried, and Chin-wen Chou
Quantum entanglement between an atom and a molecule
Nature
581
273
2020
Thu 2021-04-22 17:00 CEST
Quantum Science Seminar #45: Hot Topics
Maja Colautti
LENS
Florence — Italy
All optical frequency tuning of integrated single-molecule emitters
We address the challenge of bringing solid-state quantum
emitters all to the same resonant frequency within one chip. The
study of cooperative effects, and the possibility to scale up
quantum photonic technologies depend on such ability. Here, we
demonstrate optical frequency tuning of individual,
lifetime-limited molecules by few hundred times their natural
linewidth. The effect persists even after the pump laser is
switched off, and is attributed to a local Stark shift
associated with optically induced long-lived charge-separated
states. The experimental observation is applied to independently
tune five close-by molecules into resonance within twice their
line-width.
Tom Darras
Laboratoire Kastler Brossel
Paris — France
Hybrid entanglement in heterogeneous quantum networks
The building of quantum networks is stimulating the development
of multiple physical platforms and different types of encodings
in a heterogeneous structure allowing full functionality.
Central to this endeavour is the capability to distribute and
interconnect optical entangled states relying on different
discrete and continuous quantum variables. Here, we report an
entanglement swapping protocol involving single-photon
entanglement and hybrid entanglement between particle- and
wave-like optical qubits and demonstrate the creation of hybrid
entanglement heralded by a specific Bell-state measurement. This
ability opens up the prospect of connecting heterogeneous nodes
of a network, with the promise of increased integration and
functionalities.
Daniel Goncalves Romeu
ICFO
Barcelona — Spain
Quantum nonlinear optics based on 2D Rydberg atom arrays
In this project, we explore the combination of sub-wavelength,
two-dimensional atomic arrays, and Rydberg interactions as a
powerful platform to realize strong, coherent interactions
between individual photons with high fidelity. In particular,
the spatial ordering of the atoms guarantees efficient
atom-light interactions without the possibility of scattering
light into unwanted directions, for example, allowing the array
to act as a perfect mirror for individual photons. In turn,
Rydberg interactions enable single photons to alter the optical
response of the array within a potentially large blockade radius
R_b, which can effectively punch a large "hole" for
subsequent photons. We show that such a system enables a
coherent photon-photon gate or switch, with an error scaling
that is significantly better than the best-known scaling in a
disordered ensemble.
Thu 2021-04-29 17:00 CEST
Quantum Science Seminar #46: Quantum Thermodynamics
Alexia Auffèves
Université Grenobles Alpes
France
A short story of quantum thermodynamics
This Seminar is a fast journey through the build-up of quantum
thermodynamics, an emerging field at the crossroad between
quantum information, quantum open systems and stochastic
thermodynamics. Born at the time of industrial revolution to
optimize the exploitation of thermal resources, the concepts of
thermodynamics have been adapted to small systems where thermal
fluctuations are predominant. Extending the framework to quantum
fluctuations is a great challenge of quantum thermodynamics,
that opens exciting research lines e.g. measurement fueled
engines or thermodynamics of driven-dissipative systems. On a
more applied side, it provides the tools to optimize the
energetic consumption of future quantum computers.
Thu 2021-05-06 17:00 CEST
Quantum Science Seminar #47: Quantum Optics
Vahid Sandoghdar
Max-Planck-Institute for the Science of Light
Erlangen — Germany
Molecular Quantum Optics
Light-matter interaction at the nanometer scale lies at the
heart of elementary optical processes such as absorption,
emission or scattering. Over the past two decades, we have
realized a series of experiments to investigate the interaction
of single photons, single molecules and single nanoparticles. In
this presentation, I discuss recent studies, where we reach
unity efficiency in the coupling of single photons to single
molecules and describe our efforts to exploit this for the
realization of polaritonic states involving a controlled number
of molecules and photons. Furthermore, I report on efforts to
exploit the phononic degrees of freedom of molecules and their
environment as a quantum resource.
References
-
C. Hettich, C. Schmitt, J. Zitzmann, S. Kühn, I. Gerhardt, and V. Sandoghdar
Nanometer Resolution and Coherent Optical Dipole Coupling of Two Individual Molecules
Science
298
385
2002
-
G. Wrigge, I. Gerhardt, J. Hwang, G. Zumofen, and V. Sandoghdar
Efficient coupling of photons to a single molecule and the observation of its resonance fluorescence
Nature Physics
4
60
2008
-
Daqing Wang, Hrishikesh Kelkar, Diego Martin-Cano, Dominik Rattenbacher, Alexey Shkarin, Tobias Utikal, Stephan Götzinger, and Vahid Sandoghdar
Turning a molecule into a coherent two-level quantum system
Nature Physics
15
483
2019
Thu 2021-05-13 17:00 CEST
Quantum Science Seminar #48
Our speaker on May 13th will be Eric Hudson.
Thu 2021-05-20 17:00 CEST
Quantum Science Seminar #49
Our speaker on May 20th will be Scott Aaronson.
Thu 2021-05-27 17:00 CEST
Quantum Science Seminar #50
Our speaker on May 27th will be Markus Aspelmeyer.
Thu 2021-06-10 17:00 CEST
Quantum Science Seminar #51: Cold Molecules
John Doyle
Harvard University
Cambridge — Massachusetts — U.S.A.
Laser Cooling of Polyatomic Molecules
The tremendous scientific opportunities presented by ultracold
molecules have driven rapid progress in both the assembly of
diatomic molecules from ultracold atoms and the direct cooling
of diatomic and polyatomic molecules. Diatomic species have been
magneto-optically trapped and sub-Doppler cooled and their
collisions have been studied in several experimental systems,
including magnetic traps and merged optical tweezers. The
pioneering work that led advances in direct cooling began with
Stark deceleration, buffer-gas cooling and loading of traps,
buffer-gas beam sources, mechanical slowing, and a variety of
electromagnetic trapping and cooling mechanisms. As the field of
cold and ultracold molecules has grown, polyatomic molecules
have attracted new focus as potential novel quantum resources
that have distinct advantages (and challenges) compared to both
atoms and diatomic molecules. For example, all polyatomic
molecules have long-lived states arising from nuclear motion
with angular momentum about the internuclear axis. These states
exhibit linear, Debye-level Stark shifts at very low applied
electric fields and offer distinct Stark-shifted level
structures that are absent in laser-coolable diatomic molecules.
These and other features in polyatomic molecules can be applied
to quantum simulation, fundamental symmetry tests, searches for
dark matter, and particle physics beyond the Standard Model,
potentially at the 1 PeV scale. Generic classes of polyatomic
molecules have been identified as amenable to laser cooling into
the ultracold (~1 μK) regime. One class is that of metal oxide
radicals (MOR), which includes linear, symmetric top, and
asymmetric top species. In this talk I will discuss some of the
past experiments that brought us to this point, and the
challenges and scientific opportunities with the laser cooling
of polyatomic molecules. Results on SrOH, YbOH, CaOH and CaOCH3
will be discussed, as well as preliminary work on more complex
species.
References
-
N. J. Fitch and M. R. Tarbutt
Laser cooled molecules
arXiv
2103.00968
2021
-
I. Kozyryev, L. Baum, K. Matsuda, and J. M. Doyle
Proposal for Laser Cooling of Complex Polyatomic Molecules
ChemPhysChem
17
3641
2016
-
D. Mitra, N. B. Vilas, C. Hallas, L. Anderegg, B. L. Augenbraun, L. Baum, C. Miller, S. Raval, and J. M. Doyle
Direct Laser Cooling of a Symmetric Top Molecule
Science
369
1336
2020
Thu 2021-06-17 17:00 CEST
Quantum Science Seminar #52
Our speaker on June 17th will be Eleni Diamanti.
Thu 2021-06-24 17:00 CEST
Quantum Science Seminar #53
Our speaker on June 24th will be Helmut Katzgraber.
Thu 2021-07-01 17:00 CEST
Quantum Science Seminar #54
Our speaker on July 1st will be Nicola Poli.
Thu 2021-07-08 17:00 CEST
Quantum Science Seminar #55
Our speaker on July 8th will be Elham Kashefi.
Thu 2021-07-15 17:00 CEST
Quantum Science Seminar #56
We will have our fourth Hot Topics session on July 15th.
Thu 2021-07-22 17:00 CEST
Quantum Science Seminar #57
Our speaker on July 22nd will be Mete Atature.
Thu 2021-07-29 17:00 CEST
Quantum Science Seminar #58
We are still lookking for a speaker for July 29th.