# 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 2020-11-26 17:00 CET

Quantum Science Seminar #27: Mesoscopic Systems

University of Innsbruck and

IQOQI, Austrian Academy of Sciences

Innsbruck — Austria

IQOQI, Austrian Academy of Sciences

Innsbruck — Austria

Levitated Nanoparticles in the Quantum Regime

During the last ten years, a fast-growing scientific
activity has been devoted to understanding,
controlling and using the dynamical degrees of freedom
of levitated solid-state objects in vacuum. Levitated
nanoparticles can move, rotate and fall. They also
have solid-state internal degrees of freedom. At the
interface between the fields of cavity optomechanics
and atomic and molecular optics, the rich physics of
levitated nanoparticles provide unique opportunities
for applied and fundamental research.
In this talk, we will first motivate and review the
research activities in this field. We will then focus
on two recent results in our theory group. First, we
will discuss how the center-of-mass motion of a
micromagnet can be coupled to its internal acoustic
phononic modes. This offers a new cooling method and a
tool to probe and control the internal physics of an
isolated micromagnet. Then, we will discuss how to
optimally control the harmonic potential of a
levitated nanoparticle to quantum-delocalize its
center-of-mass motional state. This has applications
for testing quantum mechanics at large scales,
enhancing sensitivities of force sensors, and boosting
the entangling rate of two weakly interacting
nanoparticles.

References

### Thu 2020-12-03 17:00 CET

Quantum Science Seminar #28: Circuit QED

Yale University

New Haven — Connecticut — U.S.A.

New Haven — Connecticut — U.S.A.

Controlling Bosonic Modes in Circuit QED and the Application to Vibronic Molecular Simulations

Circuit quantum electrodynamics, in which microwave
cavity modes are coupled to “artificial atoms”
realized with Josephson junction qubits, has allowed
for a variety of investigations in quantum optics and
quantum information. In recent years, our team at Yale
has focused on a hardware efficient approach, where
high-Q microwave cavities serve as quantum memories.
When dispersively coupled to transmon qubits, quite
complex non-classical states can be created in these
cavities, and operations between cavities can be
enacted through parametric driving or other means. For
instance, we have recently shown high-quality
cavity-cavity swaps via a beam-splitter or conversion
operation, single and two-mode squeezing, and
engineered cross and self Kerr interactions. Finally,
one can perform strong projective measurements of the
photon number, the photon parity, or indeed any other
binary-valued operator within the multi-dimensional
Hilbert space. This system therefore has all of
capabilities of linear optical systems, but with the
addition of deterministic state preparation,
measurement, and nonlinear interactions. One way to
employ these capabilities is to directly simulate
problems which are “naturally” bosonic in nature, to
calculate vibronic spectra, Franck-Condon factors, or
nonlinear molecular dynamics. I will present
preliminary work towards using this platform as a
novel but programmable simulator for small molecules.

### Thu 2020-12-10 17:00 CET

Quantum Science Seminar #29: Rydberg Atoms

Durham University

Durham — United Kingdom

Durham — United Kingdom

Hybrid quantum interfaces using Rydberg collective encoding

Rydberg atoms has emerged as a versatile platform for
different applications in quantum technology from
computing and simulation to sensing and imaging [1].
In this talk, I will focus on one of the many Rydberg
projects in Durham. In our Rydberg quantum optics
experiment, we store optical photons in a cold atomic
ensemble in the form of Rydberg polaritons. In recent
work, we have looked at the potential of Rydberg
polaritons in the context of quantum information. We
show that Rydberg polaritons have a number of
attractive features. In particular, the combined
atomic and photonic character of the polariton [2]
allows coherent mapping between static and flying
qubits, the large dipole moments between Rydberg
states enables fast single qubit rotations, and as the
quantum information is shared amongst many atoms,
there is an in-built robustness to atom loss [3].
Finally, the robustness of collectively-encoded
Rydberg qubits to environmental noise is considered.

### Thu 2020-12-17 17:00 CET

Quantum Science Seminar #30: Precision Measurement

Universität Mainz

Mainz — Germany

Mainz — Germany

Gamma Factory: a new photonic tool for science

The Gamma Factory (GF) is an ambitious proposal
developed as part of the CERN Physics Beyond Colliders
program to operate the LHC as a novel kind of a light
source that can produce up to ~10

^{17}photons per second with energies of up to ~400 MeV. The key idea is to scatter laser photons off of partially stripped ultrarelativistic ions. The GF would enable a number of hitherto impossible experiments and can be thought of not only as a unique photon source, but also as a giant ion trap for precision physics. The first step in practical realization of the GF is a full-featured proof-of-principle experiment at the SPS that is currently being considered by CERN.### Holiday Break

The Quantum Science Seminar will take a break during the Holidays. The next seminar will be on January 14th, 2021.