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BEGIN:VEVENT
SUMMARY:A. V. Andrianov
DTSTART:20241203T130000Z
DTEND:20241203T140000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/1
DESCRIPTION:Title: Polarization squeezing in chalcogenide fibers\nby A. V. Andrianov
as part of Seminar on Quantum Optics and Related Topics\n\n\nAbstract\nWe
experimentally demonstrate the generation of polarization-squeezed light
in a short piece of solid-core chalcogenide (ChG) (As2S3) fiber via the Ke
rr effect for femtosecond pulses at 1.56μm. Directly measured squeezing o
f −2.8 dB is obtained in a setup without active stabilization. Numerical
simulations are in good agreement with the experimental results and indic
ate that the measured squeezing in our setup is mainly limited by the loss
es in the detection system rather than by the fiber properties.\n\nThe tal
k is based on the paper “Polarization squeezing in chalcogenide fibers
” published in Optics Letters 2024.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. A. Gaidash
DTSTART:20241218T130000Z
DTEND:20241218T140000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/2
DESCRIPTION:Title: Algebraic approach to dynamics of open multimode bosonic systems\
nby A. A. Gaidash as part of Seminar on Quantum Optics and Related Topics\
n\n\nAbstract\nQuantum dynamics of open continuous variable systems is a m
ultifaceted\, rapidly evolving field of both fundamental and technological
significance. An important example is a multimode photonic system coupled
to a Markovian bath (the environmental correlation times are shorter than
the system's relaxation or\ndecoherence time) so that the density matrix
dynamics is governed by the master equation of the Lindblad form. Using c
urrently available methods\, theoretical analysis of the Lindblad dynamics
complicated by intermode couplings can be rather involved even for exactl
y soluble models. The algebraic approach suggested in this paper simplifie
s both quantitative and qualitative analysis of the intermode-coupling-ind
uced effects in multimode systems by reducing the Lindblad equation to the
form determined by the effective Hamiltonian. Specifically\, we develop t
he algebraic method based on the Lie algebra of quadratic combinations of
left and right superoperators associated with matrices to study the Lindbl
ad dynamics of multimode bosonic systems coupled with a thermal bath and d
escribed by the Liouvillian superoperator that takes into account both dyn
amical (coherent) and environment mediated (incoherent) interactions betwe
en the modes. Our algebraic technique is applied to transform the Liouvill
ian into the diagonalized form by eliminating jump superoperators and solv
e the spectral problem. The temperature independent effective non-Hermitia
n Hamiltonian\, $\\hat{H}_{\\ind{eff}}$\, is found to govern both the dia
gonalized Liouvillian and the spectral properties. It is shown that the Li
ouvillian exceptional points are represented by the points in the paramete
r space where the matrix\, $H$\, associated with $\\hat{H}_{\\ind{eff}}$
is non-diagonalizable. We use our method to derive the low-temperature ap
proximation for the superpropagator and to study the special case of a two
mode system representing the photonic polarization modes\,e.g. optical po
larization qubit.For this system\, we describe the geometry of exceptional
points in the space of frequency and relaxation vectors parameterizing th
e intermode couplings and\, for a single-photon state\, evaluate the time
dependence of the density matrix.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:B. A. Malomed
DTSTART:20250109T130000Z
DTEND:20250109T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/3
DESCRIPTION:Title: Trapping wave fields in an expulsive potential by means of linear cou
pling\nby B. A. Malomed as part of Seminar on Quantum Optics and Relat
ed Topics\n\n\nAbstract\nWe demonstrate the existence of confined states i
n one- and two-dimensional (1D and 2D) systems of two linearly-coupled com
ponents\, with the confining harmonic-oscillator (HO) potential acting upo
n one-component\, and an expulsive anti -HO potential acting upon the othe
r. The systems can be implemented in optical and BEC dual-core waveguides.
In the 1D linear system\, codimension-one solutions are found in an exact
form for the ground state (GS) and dipole mode (the first excited state).
Generic solutions are produced by the variational approximation\, and are
found in a numerical form. Exact codimension-one solutions and generic nu
merical ones are obtained for the GS and vortex states in the 2D system. B
oth the trapped and anti-trapped components of the bound states may be dom
inant ones\, in terms of the norm. The localized modes may be categorized
as bound states in continuum\, as they coexist with delocalized ones. The1
D states\, as well as the GS in 2D\, are weakly affected and remain stable
if the self-attractive or repulsive nonlinearity is added to the system.
The self-attraction makes the vortex states unstable against splitting\, w
hile they remain stable under the action of the self-repulsion.\n\nPublica
tions: N. Hacker and B. A. Malomed\, Nonlinear dynamics of wave packets in
tunnel-coupled harmonic-oscillator traps\, Symmetry 13\, 372 (2021)\; Tra
pping wave fields in an expulsive potential by means of linear coupling\,
Phys. Rev. E 105\, 034213 (2022).\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Z. Khoury (Universidade Federal Fluminense)
DTSTART:20250121T130000Z
DTEND:20250121T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/4
DESCRIPTION:Title: Recognition of Light Orbital-Angular-Momentum Superpositions for Quan
tum Communication\nby A. Z. Khoury (Universidade Federal Fluminense) a
s part of Seminar on Quantum Optics and Related Topics\n\n\nAbstract\nWe s
tudy the tomography of spatial qudits encoded on structured light photons
in the space of fixed order transverse modes. While direct position measur
ements with cameras do not provide an informationally complete Positive Op
erator Valued Measure (POVM)\, this property is achieved with the use of a
stigmatic transformation\, allowing full characterization of the spatial q
uantum state from simple intensity measurements in both the intense and in
the low photocount regimes. These methods are useful for classical and qu
antum communication with structured light and will be tested in a quantum
network being set up in the Rio de Janeiro metropolitan area.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. D. Kiselev
DTSTART:20250206T130000Z
DTEND:20250206T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/5
DESCRIPTION:Title: Lindblad dynamics of multi-mode photonic systems: Exceptional points
and speed of evolution\nby A. D. Kiselev as part of Seminar on Quantum
Optics and Related Topics\n\n\nAbstract\nThis talk deals with intermode-i
nteraction-induced effects in dynamics of open multi-mode photonic systems
representing a family of continuous variable systems whose density matrix
dynamics is governed by the master equation of the Lindblad form (the so-
called Gorini-Kossakowski-Sudarshan-Lindblad master equation). We briefly
discuss two analytical techniques to perform theoretical analysis of the L
indblad dynamics complicated by intermode couplings: (a) an algebraic appr
oach based on the algebra of bilinear superoperators recently suggested in
[Gaidash et al.\, arXiv:2412.13890[quant-phys]] and (b) the method of cha
racteristic functions. We employ exact solution of the thermal bath Lindbl
ad master equation with the Liouvillian superoperator that takes into acco
unt both dynamic (coherent) and environment induced (incoherent) intermode
couplings to study the speed of evolution and the quantum speed limit (QS
L) times of an open multi-mode bosonic system. For Gaussian states\, we de
rive explicit expressions for the evolution speed and the QSL times. Gener
al analytical results are applied to the special case of a two-mode system
where the intermode couplings can be parametrized using the two intermode
coupling vectors: the frequency vector and the relaxation rate vector. Fo
r this system\, we describe the geometry of Liouvillian exceptional points
in the space of these vectors and present a number of numerical results o
n evolution of Gaussian (two-mode squeezed states) and non-Gaussian (polar
ization qubit states) states.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:J. E. Gough
DTSTART:20250213T130000Z
DTEND:20250213T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/6
DESCRIPTION:Title: Non-Markovian Quantum Stochastic Models\nby J. E. Gough as part o
f Seminar on Quantum Optics and Related Topics\n\n\nAbstract\nWe give a de
rivation of the non-Markovian quantum state diffusion equation of Diósi a
nd Strunz starting from a model of a quantum mechanical system coupled to
a bosonic bath. We show that the complex trajectories arises as a conseque
nce of using the Bargmann-Segal (complex wave) representation of the bath.
In particular\, we construct a reproducing kernel Hilbert space for the b
ath auto-correlation and realize the space of complex trajectories as a Hi
lbert subspace. The reproducing kernel naturally arises from a feature spa
ce where the underlying feature space is the one-particle Hilbert space of
the bath quanta. We exploit this to derive the unravelling of the open qu
antum system dynamics and show equivalence to the equation of Diósi and S
trunz. We also give an explicit expression for the reduced dynamics of a t
wo-level system coupled to the bath via a Jaynes-Cummings interaction and
show that this does indeed correspond to an exact solution of the Diósi-S
trunz equation. Finally\, we discuss the physical interpretation of the co
mplex trajectories and show that they are intrinsically unobservable.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:P. Shukla
DTSTART:20250216T130000Z
DTEND:20250216T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/7
DESCRIPTION:Title: Entanglement dynamics of many body quantum states with evolving syste
m conditions\nby P. Shukla as part of Seminar on Quantum Optics and Re
lated Topics\n\n\nAbstract\nThe entanglement analysis of a pure state of a
many body quantum system requires a prior information about its density m
atrix/ state matrix\, obtained in principle by solving the Hamiltonian mat
rix. The missing information due to complexity of the many body interactio
ns however renders it necessary to consider an ensemble of Hamiltonians an
d thereby an ensemble for each eigenstate. This in turn leaves a statistic
al description of the entanglement measures as the only option. For an ens
emble to appropriately represent a many body Hamiltonian\, the ensemble pa
rameters must be determined from the system parameters. A variation of the
latter is therefore expected to manifest in variation of the the ensemble
for each eigenstate and thereby their entanglement aspects. We theoretica
lly analyze the effect of varying system conditions on the eigenstates of
a wide range of Hamiltonians and derive a common mathematical formulation
for the bipartite entanglement statistics. As the system information in th
e formulation enters through a single functional of the ensemble parameter
s\, this implies the analogy of statistics for different eigenstate ensemb
les (non-Haar type) if they share the same complexity parameter and thereb
y reveals a deep web of connection underlying among quantum states of diff
erent Hamiltonians (with same global symmetry class). Besides revealing un
iversality among non-haar states\, the information is also relevant for qu
antum state engineering e.g. how to achieve a near Haar random state start
ing from a random non-ergodic state.\n\nWork done in collaboration with my
PhD student Devanshu Sekhar.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S.P. Vyatchanin
DTSTART:20250220T130000Z
DTEND:20250220T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/8
DESCRIPTION:Title: Broadband variational measurement of a classical force using strongly
nondegenerate dichromatic optical pump\nby S.P. Vyatchanin as part of
Seminar on Quantum Optics and Related Topics\n\n\nAbstract\nMaximal sensi
tivity of classical force detectors utilizing nonlinear opto-mechanical tr
ansducers is generally de\nfined by the standard quantum limit resulting
from the contamination of the detected signal with noncommuting\nquantum n
oises. This restriction can be circumvented by the optimal detection proto
cols. We here show theoretically that interrogating a resonant opto-mechan
ical displacement transducer with a strongly nondegenerate dichromatic opt
ical probe enables a quantum back-action evading measurement of a classica
l force acting on the mechanical oscillator being a part of the opto-mecha
nical transducer.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:D. I. Salykina
DTSTART:20250227T130000Z
DTEND:20250227T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/9
DESCRIPTION:Title: Intracavity squeezing as a tool for improving the quantum nondemoliti
on (QND) measurement scheme\nby D. I. Salykina as part of Seminar on Q
uantum Optics and Related Topics\n\n\nAbstract\nWe consider the scheme of
quantum nondemolition measurement of optical quanta based on the Kerr nonl
inearity in an optical microresonator. We demonstrate that by using the in
tracavity squeezing of a probe beam it is possible to cancel the interferi
ng effect of self-phase modulation. This results in improvement of scheme
sensitivity\, allowing it theoretically to approach the single-photon sens
itivity. Our estimates show that generation and verification of bright non
-Gaussian quantum states with mean photon numbers up to 1000 is feasible.\
n\nPublications:\n\nBalybin S.\, Salykina D.\, Khalili F. Ya. (2023). Impr
oving the sensitivity of Kerr quantum nondemolition measurement via squeez
ed light. Physical Review A\, 108(5)\, 053708.\n\nSalykina D.\, Balybin S.
\, Khalili F. Ya. (2025). Intracavity squeezing for a Kerr quantum nondemo
lition measurement scheme. Physical Review A\, 111(1)\, 013715.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E. A. Anashkina
DTSTART:20250312T130000Z
DTEND:20250312T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/10
DESCRIPTION:Title: Symmetry breaking of counterpropagating Raman waves in optical micro
resonators: unexpected findings\nby E. A. Anashkina as part of Seminar
on Quantum Optics and Related Topics\n\n\nAbstract\nRecently\, symmetry b
reaking and related issues in high-Q nonlinear optical microresonators hav
e been of growing interest for fundamental research and photonic device de
velopment. Most studies employ Kerr nonlinearity\, but this is not the onl
y way. We present our recent results on symmetry breaking of counterpropag
ating Raman waves at Stokes frequencies in a bidirectionally pumped silica
microresonator. We experimentally demonstrate symmetry-broken Raman lasin
g with previously unreported features such as intensity switching of count
erpropagating waves and symmetry restoring during pump frequency sweeping.
Symmetric and asymmetric stationary states have been found theoretically\
, but asymmetric states after a pitchfork bifurcation have proven to be un
stable. Such behavior is surprising\, since in the case of pure Kerr nonli
nearity (without stimulated Raman scattering)\, a pair of stable asymmetri
c states is born after a pitchfork bifurcation\, and the symmetric solutio
n becomes unstable. The explanation of our experimental findings is based
on a weak asymmetry in the scheme\, which dramatically changes the dynamic
behavior of the system. This is confirmed by numerical simulations with a
dded back reflection for a single Raman wave.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:N. G. Veselkova
DTSTART:20250319T124500Z
DTEND:20250319T134500Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/11
DESCRIPTION:Title: Creation and manipulation of Schrödinger cat states based on semicl
assical predictions\nby N. G. Veselkova as part of Seminar on Quantum
Optics and Related Topics\n\n\nAbstract\nWe consider the generation of Sch
rödinger cat states using a quantum measurement-induced logical gate wher
e entanglement between the input state of the target oscillator and the Fo
ck state of the ancillary system produced by the quantum non-demolition en
tangling CZ operation is combined with the homodyne measurement. We utiliz
e the semiclassical approach to construct both the input-output mapping of
the field variables in the phase space and the wave function of the outpu
t state. This approach is found to predict that the state at the gate outp
ut is represented by a minimum disturbed cat-like state which is a superpo
sition of two initial state copies symmetrically displaced by momentum var
iable. For the target oscillator prepared in the coherent state\, we show
that the fidelity between the exact solution for the gate output state and
the “perfect” Schrödinger cat reconstructed from the semiclassical t
heory can reach high values exceeding 0.99.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:V.N. Sivkin
DTSTART:20250328T120000Z
DTEND:20250328T133000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/12
DESCRIPTION:Title: Tomography and Radon transform\nby V.N. Sivkin as part of Semina
r on Quantum Optics and Related Topics\n\n\nAbstract\nMathematical tomogra
phy is a section of mathematics that describes methods for determining the
structure of an object using scattering data. Such problems arise in micr
oscopy\, medicine\, and technical control. In this report\, we will write
out the basic differential equation of X-ray tomography. In the course of
its solution\, the Radon transform arises. We will establish a connection
between the Fourier transform and the Radon transform\, and get acquainted
with the methods of its inversion.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:D.B. Zotev
DTSTART:20250410T130000Z
DTEND:20250410T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/13
DESCRIPTION:Title: On continuous observables in quantum mechanics\nby D.B. Zotev as
part of Seminar on Quantum Optics and Related Topics\n\n\nAbstract\nThe t
heory of continuous observables in quantum mechanics has been arising mist
rust among mathematicians. Von Neumann banished from it the delta-function
and such exotic entities as "Hermitian product matrices" with continuous
indices and quasi-elements in the form of generalized functions. Thanks to
von Neumann the paradigm has been spread according to which the state spa
ce of a quantum system must only be Hilbert. De'facto he replaced Copenhag
en quantum mechanics by a new theory with new physical consequences. In a
ddition\, along with the delta-function\, quantum mechanics in many ways l
ost its heuristic power. Dirac brilliantly anticipated the theory of gene
ralized functions and\, in fact\, there was no need for such a reform. The
report presents the theory of continuous observables in the formal form g
iven to it by Heisenberg and Dirac. At the same time\, Dirac's approach is
strictly formalized within the framework of the theory of generalized fun
ctions. But Hilbert spaces are met here too.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I.E. Protsenko
DTSTART:20250415T120000Z
DTEND:20250415T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/14
DESCRIPTION:Title: Theoretical modelling of superradiant lasers and other open quantum
resonant systems\nby I.E. Protsenko as part of Seminar on Quantum Opti
cs and Related Topics\n\n\nAbstract\nAn approach for solving the stationar
y nonlinear quantum Langevin equations for micro-lasers and other small re
sonant optical devices (for nonlinear optics\, plasmonics etc.) is present
ed. The method uses frequency dependent operators and calculates the mean
fluctuation power spectra and photon number. Various approximations for fi
nding analytical expressions are shown. Results for thresholdless lasing\,
collective Rabi splitting\, super-thermal photon statistics and the power
increase by the population fluctuations for the superradiant lasers are d
iscussed.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. Lakshmi Bala
DTSTART:20250425T130000Z
DTEND:20250425T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/15
DESCRIPTION:Title: Optimal sensing of photon addition and subtraction on quantized ligh
t\nby S. Lakshmi Bala as part of Seminar on Quantum Optics and Related
Topics\n\n\nAbstract\nPhoton addition to\, and subtraction from quantum s
tates of light is of immense current interest\, both experimentally and th
eoretically. We identify a set of markers of photon addition to coherent l
ight and nonclassical single mode states of light such as the squeezed vac
uum and the cat states\, which are directly computable from relevant optic
al tomograms. These markers quantify the ‘distance’ between probabilit
y density functions corresponding to different states. Examples of such ma
rkers are the Wasserstein distance\, the Kullback Leibler divergence and t
he Bhattacharyya distance.\nAlthough the details in the manner in which th
ese markers vary with changes in relevant parameters\, depends on the stat
e concerned\, they are\, in general\, sensitive to the underlying interfer
ence structures that arise in the tomogram after photon addition/subtracti
on. Our procedure is universally applicable to the cat and squeezed states
\, the former displaying the characteristic negativity in its Wigner funct
ion\, while the latter does not do so. We explicate this in the case of th
e squeezed vacuum and even coherent states and show that photon addition (
or subtraction) is mirrored in the shift in the intensity of specific regi
ons in the tomogram.\nIn the case of coherent light\, the amplification ga
in due to photon addition\, and the dependence of quadrature variances on
relevant parameters\, are calculated from the tomograms (circumventing sta
te reconstruction)\, and compared with results obtained (after state recon
struction)\, in a recent experiment reported in the literature. Our result
s match well with the fidelity and variance plots obtained by the experime
nters.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ray-Kuang Lee
DTSTART:20250430T130000Z
DTEND:20250430T140000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/16
DESCRIPTION:Title: Adding or subtracting a single photon is the same\, but only for pur
e squeezed vacuum states\nby Ray-Kuang Lee as part of Seminar on Quant
um Optics and Related Topics\n\n\nAbstract\nThe addition of a single photo
n to a light field can lead to exactly the same outcome as the subtraction
of a single photon: starting from the same initial state\, both procedure
s can generate the same final quantum state. We prove that this identity-o
f-outcome is true for pure squeezed vacuum states of light\, and in some s
ense only for those. We show that mixed states can show this identity-of-o
utcome for the addition or subtraction of a photon if they are generated f
rom the incoherent sums of pure squeezed vacuum states with the same squee
zing. We point out that our results give a reinterpretation to the fact th
at pure squeezed.\n\nPublication:\n\nOle Steuernagel\, Shao-Hua Hu\, and R
ay-Kuang Lee\, APL Quantum 2\, 016117 (2025)\; https://doi.org/10.1063/5.0
246230\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:R. Sh. Kalmetev
DTSTART:20250527T130000Z
DTEND:20250527T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/17
DESCRIPTION:Title: On Averaging of One-Parameter Semigroups and Their Generators\nb
y R. Sh. Kalmetev as part of Seminar on Quantum Optics and Related Topics\
n\n\nAbstract\nThe talk discusses methods for averaging one-parameter semi
groups and their generators\, focusing on random unbounded operators in Hi
lbert spaces. Key findings include the construction of generalized expecta
tions through Chernoff equivalence\, illustrative examples for resolvent a
nd semigroup averaging\, and the role of Feynman formulas in approximating
quantum evolution operators. The results highlight the flexibility and li
mitations of these methods\, offering insights into their use in dissipati
ve dynamics\, quantization ambiguities\, and stochastic differential equat
ions in mathematical physics.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:N. S. Arefyeva
DTSTART:20250617T130000Z
DTEND:20250617T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/18
DESCRIPTION:Title: Non-Markovian entropy production and its connection to global entang
lement in quantum chaos\nby N. S. Arefyeva as part of Seminar on Quant
um Optics and Related Topics\n\n\nAbstract\nWe focus on the problem of ide
ntifying dynamical signatures of quantum behavior\, particularly quantum c
haos. Recently\, we proposed a method for efficiently computing the dynami
cs of an open quantum system\, based on emergent integrals of motion that
dynamically form in the environment after a local quench. These integrals
carry away the system’s entanglement entropy.\n\nWe show that in the Mar
kovian limit\, resembling ancilla-based models\, entropy production grows
linearly and integrable and chaotic behavior are indistinguishable. In con
trast\, in the non-Markovian regime\, entropy production closely follows t
he Meyer–Wallach global entanglement measure and serves as a sensitive p
robe of quantum chaos. Thus\, we propose non-Markovian entropy production
as a marker of quantum chaos.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. A. Aleksandrov
DTSTART:20250707T130000Z
DTEND:20250707T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/19
DESCRIPTION:Title: Quantum analog of classical Arnold tongues\nby A. A. Aleksandrov
as part of Seminar on Quantum Optics and Related Topics\n\n\nAbstract\nI
will review papers by Lee et. al related to synchronization of open quantu
m systems. Each system is nothing more than a simple harmonic oscillator\,
interacting with an environment. To start with\, I present the essential
facts about phase-locking and synchronization in simple dynamical system o
n torus. Next one will see how does the quatum limit cylce can appear\, th
en we will see how does the classical synchronization domain (Arnold tongu
e) evolves into its quantum version. The talk is on physical level of rigo
ur.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. A. Gorlach
DTSTART:20250717T120000Z
DTEND:20250717T133000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/20
DESCRIPTION:Title: Time-optimal transfer of the quantum state in long qubit arrays\
nby M. A. Gorlach as part of Seminar on Quantum Optics and Related Topics\
n\n\nAbstract\nRecent technological advances have allowed the fabrication
of large arrays of coherently operating coupled qubits\, serving as protot
ypes for quantum processors. However\, the optimal control of such systems
is notoriously challenging because of the extremely large number of degre
es of freedom. The lack of such control limits the potential of large-scal
e quantum systems.\nIn this talk\, I will discuss a model problem of quant
um state transfer in a large nearest-neighbor-coupled qubit array. I will
present the optimal control strategy that simultaneously achieves maximal
fidelity and minimal transfer time\, reaching the quantum speed limit in a
lattice with time-varying couplings. \n\nRelated paper:\n\nhttps://arxiv.
org/abs/2501.11933\, accepted to Physical Review Letters\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. V. Iorsh
DTSTART:20250725T130000Z
DTEND:20250725T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/21
DESCRIPTION:Title: Polaron effect in waveguide quantum optomechanics\nby I. V. Iors
h as part of Seminar on Quantum Optics and Related Topics\n\n\nAbstract\nI
n my talk I will discuss the impact of the quantized mechanical motion of
optically trapped atoms\, arranged in proximity to a one-dimensional waveg
uide\, on the propagation of polariton modes. Our study identifies a regim
e of resonant phonon-assisted mixing between lower and upper polaritons\,
resulting in a pronounced polaron effect. This effect is characterized by
the formation of new band gaps and the appearance of weakly dispersive sta
tes within the original polariton band gap. The polaron spectrum\, which c
an be directly probed via resonant elastic scattering\, provides novel opp
ortunities for quantum optical applications. These findings open avenues f
or enhanced control in state-of-the-art waveguide quantum electrodynamics
experiments with cold atoms\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. V. Bastrakova
DTSTART:20250728T130000Z
DTEND:20250728T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/22
DESCRIPTION:Title: Josephson "flying qubit" revival: Flux-based control optimization\nby M. V. Bastrakova as part of Seminar on Quantum Optics and Related To
pics\n\n\nAbstract\nA decade ago\, Josephson "flying qubits" based on adia
batic superconducting logic cells showed promise as quantum data buses\, b
ut their development stalled due to the incompatibility of traditional qub
it control methods with their design. We revisit this concept by exploring
the control of the inductively shunted two-junction superconducting inter
ferometer (adiabatic quantum flux parametron\, AQFP) in the quantum regime
using unipolar magnetic field pulses generated by adiabatic superconducti
ng electronics. Our research demonstrates the feasibility of high fidelity
quantum operations (fidelity more than 99.99 percent) in this system via
Landau–Zener tunneling. To this end\, a method is proposed for selecting
the duration and shape of control pulses to eliminate unwanted leakage in
to high-lying states in AQFP-based systems.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. Yu. Karasev
DTSTART:20250806T130000Z
DTEND:20250806T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/23
DESCRIPTION:Title: Projection approach for composite open quantum systems\nby A. Yu
. Karasev as part of Seminar on Quantum Optics and Related Topics\n\n\nAbs
tract\nThis report presents the application of the Nakajima–Zwanzig proj
ection method to the derivation of kinetic equations for systems treated a
s weakly interacting open subsystems. As illustrative examples\, we analyz
e the Jaynes–Cummings model with dissipation and the spontaneous paramet
ric down-conversion model involving two dissipative modes. For both system
s\, the approach enables a systematic derivation of corrections to the par
ametric approximation by accounting for quantum depletion of the pumping f
ield.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. S. Sysoev
DTSTART:20250827T130000Z
DTEND:20250827T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/24
DESCRIPTION:Title: Some Practical Problems of Quantum Gate Teleportation (QGT)\nby
S. S. Sysoev as part of Seminar on Quantum Optics and Related Topics\n\n\n
Abstract\nQuantum teleportation is unquestionably an important resource\,
especially in the one-way computation model. However\, we will focus on th
e circuit-based model and explore what this technique can contribute to it
s toolset. Quantum algorithms can benefit from teleportation if we telepor
t gates rather than states. This idea was investigated two decades ago by
Gottesman and Chuang\, whose paper optimistically claimed that teleportati
on is a universal computational resource. \nApart from teleporting the CX
gate within the KLM protocol\, though\, it is hard to find convincing pra
ctical uses for this technique. Furthermore\, the derivation of the CX-gat
e procedure itself was never fully clarified. In this talk we will revisit
their method\, extend it to the Toffoli gate\, offer fresh motivation for
pursuing gate teleportation\, and identify the obstacles encountered alon
g the way.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A. S. Solntsev
DTSTART:20251014T060000Z
DTEND:20251014T083000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/25
DESCRIPTION:Title: Nonlinear quantum optics: from photonic chips to nanoscale\nby A
. S. Solntsev as part of Seminar on Quantum Optics and Related Topics\n\n\
nAbstract\nQuantum optics has a range of applications including secure com
munication\, precise sensing\, and ultrafast computing. Optical nonlineari
ties have long been utilised as a source of quantum light. Nowadays\, nonl
inear quantum photonics is undergoing rapid miniaturisation\, moving from
bulk optics\, to photonic chips\, and\, more recently\, to nano-scale comp
onents. This transition is what this talk is about.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:M. A. Gavreev
DTSTART:20251016T130000Z
DTEND:20251016T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/26
DESCRIPTION:Title: Tensor Networks: From Numerical Methods to Understanding Quantum Sys
tems\nby M. A. Gavreev as part of Seminar on Quantum Optics and Relate
d Topics\n\n\nAbstract\nTensor networks are a modern mathematical language
that allows for a compact and efficient description of many-body quantum
states\, where direct computation becomes impossible. This talk discusses
how this approach helps to understand the structure of entanglement and th
e dynamics of systems with a large number of particles\, as well as how it
is used for the numerical solution of quantum mechanical problems. The ma
in ideas underlying tensor networks\, intuitive examples of how they work\
, and key directions of practical application — from modeling many-body
quantum systems to describing states of light — will be presented. Speci
al attention is given to how tensor methods unify theory\, computation\, a
nd experiment\, opening new possibilities for the study of quantum systems
.\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. D. Remizov
DTSTART:20251023T130000Z
DTEND:20251023T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/27
DESCRIPTION:Title: Estimates on the rate of convergence of Chernoff approximations to C
0 -semigroups (Part 1 of 2)\nby I. D. Remizov as part of Seminar on Qu
antum Optics and Related Topics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:I. D. Remizov
DTSTART:20251030T130000Z
DTEND:20251030T143000Z
DTSTAMP:20260422T225928Z
UID:QOARTseminar/28
DESCRIPTION:Title: Estimates on the rate of convergence of Chernoff approximations to C
0 -semigroups (Part 2 of 2)\nby I. D. Remizov as part of Seminar on Qu
antum Optics and Related Topics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/QOARTseminar/28/
END:VEVENT
END:VCALENDAR