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## Accuracy of the quantum regression theorem for photon emission from a quantum dot

Physical Review Letters. 2021. Vol. 127. No. 10. Article 100402.

The quantum regression theorem (QRT) is the most widely used tool for calculating multitime correlation functions for the assessment of quantum emitters. It is an approximate method based on a Markov assumption for environmental coupling. In this Letter we quantify properties of photons emitted from a single quantum dot coupled to phonons. For the single-photon purity and the indistinguishability, we compare numerically exact path-integral results with those obtained from the QRT. It is demonstrated that the QRT systematically overestimates the influence of the environment for typical quantum dots used in quantum information technology.

D. S. Shapiro, Pogosov W. V., Yu. E. Lozovik, Physical Review A: Atomic, Molecular, and Optical physics 2020 Vol. 102 No. 2 P. 023703-1-023703-15

In view of recent proposals for the realization of anisotropic light-matter interaction in such platforms as (i) nonstationary or inductively and capacitively coupled superconducting qubits, (ii) atoms in crossed fields, and (iii) semiconductor heterostructures with spin-orbital interaction, the concept of a generalized Dicke model, where coupling strengths of rotating wave and counter-rotating wave terms are ...

Added: October 30, 2020

Elena R. Loubenets, Kuznetsov S., Louis Hanotel, Journal of Physics A: Mathematical and Theoretical 2024 Vol. 57 No. 5 Article 055302

For the maximal violation of all Bell inequalities by an arbitrary pure two-qudit state of any dimension, we derive a new lower bound expressed via the concurrence of this pure state. This new lower bound and the upper bound on the maximal Bell violation, found in [J. Phys. A: Math. Theor. 55, 285301 (2022)] and ...

Added: January 6, 2024

Cosacchi M., Seidelmann T., Ungar F. et al., Physical Review B: Condensed Matter and Materials Physics 2020 Vol. 101 Article 205304

We have simulated the time evolution of the photon number distribution in a semiconductor quantum- dot–microcavity system driven by chirped laser pulses and compare with unchirped results. When phonon interactions with the dot are disregarded—thus corresponding to the limit of atomic cavity systems—chirped pulses generate photon number distributions that change their shape drastically in the ...

Added: February 24, 2022

Barabanenkov M. Y., Kalyabin D., Nikitov S., Journal of Experimental and Theoretical Physics 2020 Vol. 130 No. 4 P. 549-554

Simultaneous quantum correlations between two spins in magnetic nanostructures are considered in the model of a linear chain of a finite number of atoms with exchange interaction between electron spins of neighboring atoms in the framework of the Heisenberg ferromagnetism theory. We assume that in the initial state, the spins of all chain atoms except the first ...

Added: October 26, 2021

Sergeev T., Zyablovsky A., Andrianov E. et al., QUANTUM 2023 Vol. 7 Article 982

Exceptional point (EP) is a spectral singularity in non-Hermitian systems. The passing over the EP leads to a phase transition, which endows the system with unconventional features that find a wide range of applications. However, the need of using the dissipation and amplification limits the possible applications of systems with the EP. In this work, ...

Added: August 22, 2023

Sergeev T. T., Zyablovsky A. A., Andrianov E. S. et al., Scientific Reports 2021 Vol. 11 Article 24054

We demonstrate a new type of non-Hermitian phase transition in open systems far from thermal equilibrium, which can have place in the absence of an exceptional point. This transition takes place in coupled systems interacting with reservoirs at different temperatures. We show that the spectrum of energy flow through the system caused by the temperature ...

Added: January 2, 2022

Elistratov A., Remizov S., Yurii Lozovik, Physical Review A: Atomic, Molecular, and Optical physics 2020 Vol. 102 No. 4 P. 042224-1-042224-13

Using semion substitution for spin variables we perform an ab initio derivation of effective action for an open quantum two-level system. For this purpose, we introduce, by using the Hubbard-Stratonovich transformation a two-time complex quantum field which average value plays the role of the Green's function for the spin variables. The field thus introduced allows ...

Added: October 30, 2020

Sergeev T. T., Zyablovsky A. A., Andrianov E. S. et al., Journal of the Optical Society of America B: Optical Physics 2023 Vol. 40 No. 11 P. 2743-2750

An ultra-strong coupling regime takes place in a compound system when a coupling strength between the subsystems exceeds one tenth of the system eigenfrequency. It transforms into a deep-strong coupling regime when the coupling strength exceeds the system eigenfrequency. In these regimes, there are difficulties with description of relaxation processes without explicit considering of environment ...

Added: August 22, 2023

Alliluev A., Makarov D., Asriyan N. et al., Physics Letters A 2022 Vol. 453 Article 128492

Dynamics of exciton-polaritonic Bose-Einstein condensate is considered. We construct the stochastic Gross-Pitaevskii equation, where condensate is coupled to the excitonic reservoir in the non-Markovian regime. This equation is utilized for study of condensate formation. It is found that increasing of temperature results in transition from spatially uniform to fragmented pattern with onset of numerous vortices. ...

Added: October 24, 2022

Cygorek M., Cosacchi M., Vagov A. et al., Nature Physics 2022 Vol. 18 No. 6 P. 662-668

Studies of the dynamics of open quantum systems are limited by the large Hilbert space of typical environments, which is too large to be treated exactly. In some cases, approximate descriptions of the system are possible, for example, when the environment has a short memory time or only interacts weakly with the system. Accurate numerical ...

Added: May 21, 2022

Chryssomalakos C., Flores-Delgado A. G., Guzman Gonzalez E. et al., Working papers by Cornell University. Series math "arxiv.org" 2024

We show that the concept of total variance of a spin state, defined as the average of the variances of spin projection measurements along three orthogonal axes, also gives the rotational speed of the state in projective space, averaged over all rotation axes. We compute the addition law, under system composition, for this quantity and ...

Added: February 1, 2024

A. S. Holevo, Giovannetti V., Mari A., Nature Communication 2014 Vol. 5 P. 3826

We show that every output state of a phase insensitive bosonic Gaussian channel is majorized by the output of the channel applied to an arbitrary coherent state. The proof is based on the optimality of coherent states for the minimization of strictly concave output functionals. Moreover we show that coherent states are the unique optimizers. ...

Added: May 20, 2014

Arutyunov, K.Y., Astafiev O. V., Ioffe L. B. et al., Nature 2012 Vol. 484 No. 7394 P. 355-358

A hundred years after the discovery of superconductivity, one
fundamental prediction of the theory, coherent quantum phase
slip (CQPS), has not been observed. CQPS is a phenomenon exactly
dual1 to the Josephson effect; whereas the latter is a coherent
transfer of charges between superconducting leads2,3, the former
is a coherent transfer of vortices or fluxes across a superconducting
wire. In contrast ...

Added: March 24, 2014

Neliubov A., Eremchev I., Drachev V. et al., Physical Review B: Condensed Matter and Materials Physics 2023 Vol. 107 No. 8 Article L081406

Microdiamonds with color centers have unique photophysical properties. We discover extremely narrow spectral lines with full width at half maximum down to 0.5 nm (≈390 GHz at wavelength 630.15 nm) at room temperature in photoluminescence of numerous high-pressure–high-temperature microdiamonds. Correlation spectroscopy proves that these lines originate from single photon emitters. Comprehensive experimental characterization of the ...

Added: May 19, 2023

Remizov S., Zhukov A. A., Shapiro D. et al., Physical Review A: Atomic, Molecular, and Optical physics 2017 Vol. 96 No. 4 Article 043870

We consider a dissipative evolution of a parametrically driven qubit-cavity system under the periodic modulation of coupling energy between two subsystems, which leads to the amplification of counter-rotating processes. We reveal a very rich dynamical behavior of this hybrid system. In particular, we find that the energy dissipation in one of the subsystems can enhance ...

Added: October 29, 2021

Кулик С. П., Kravtsov K., Молотков С. Н., Laser Physics Letters 2022 Vol. 19 No. 2 Article 025203

The analysis of the security of quantum key distribution systems with respect to an attack with nondemolishing measurement of the number of photons (photon number splitting—PNS attack) is carried out under the assumption that in the communication channel in each parcel there is a pure Fock state with a different number of photons, and the ...

Added: December 27, 2022

А. А. Макаров, В. И. Юдсон, Квантовая электроника 2020 Т. 50 № 3 С. 225-230

Some collective excitations of an ensemble of closely spaced (two-level) atoms can be characterised by extremely low rates of radiation decay, which is of considerable interest for storing quantum information. Such (dark) states are realised, for example, in planar geometry when atoms are located at the nodes of a regular polygon. However, the decay rate ...

Added: November 12, 2020

Moshkova M., Divochiy A., Morozov P. et al., Journal of the Optical Society of America B: Optical Physics 2019 Vol. 36 No. 3 P. B20-B25

The use of improved fabrication technology, highly disordered NbN thin films, and intertwined section topology makes it possible to create high-performance photon-number-resolving superconducting single-photon detectors (PNR SSPDs) that are comparable to conventional single-element SSPDs at the telecom range. The developed four-section PNR SSPD has simultaneously an 86±3%86±3% system detection efficiency, 35 cps dark count rate, ∼2 ns∼2 ns dead time, and maximum ...

Added: January 9, 2019

Elena R. Loubenets, Louis Hanotel, Kuznetsov S., / Cornell University. Series arxiv/org "quant-ph". 2023. No. 2303.16794.

For the maximal violation of all Bell inequalities by an arbitrary pure two-qudit state of any dimension, we derive a new lower bound expressed via the concurrence of this pure state. This new lower bound and the upper bound on the maximal Bell violation, found in [J. Phys. A: Math. Theor. 55, 285301 (2022)] and ...

Added: April 10, 2023

Elistratov A., Remizov S., Lozovik Y., Physical Review A: Atomic, Molecular, and Optical physics 2020 Vol. 102 No. 3 Article 042224

Using semion substitution for spin variables we perform an ab initio derivation of effective action for an open quantum two-level system . For this purpose, we introduce, by using the Hubbard-Stratonovich transformation a two-time complex quantum field which average value plays the role of the Green's function for the spin variables. The field thus introduced allows us ...

Added: October 29, 2021

Ланкин А. В., Norman G., М. : Физматлит, 2023

Книга посвящена текущему состоянию квантовой механики, перспективам еe развития и усилению ее влияния на научно-технический прогресс. В основе утверждение Э. Леггетта 2002 г., что квантовая механика — это не просто «теория», а радикальное изменение парадигмы в истории человеческой мысли. Мы дали ей название «неокопенгагенская», чтобы подчеркнуть как развитие по сравнению с копенгагенской интерпретацией, так и преемственность с ней. Изложены ...

Added: November 17, 2023

Shapiro D. S., Rubtsov A. N., Remizov S. V. et al., Physical Review A: Atomic, Molecular, and Optical physics 2019 Vol. 99 No. 6 Article 063821

The analysis of single-mode photon fluctuations and their counting statistics at the superradiant phase transition is presented. The study concerns the equilibrium Dicke model in a regime where the Rabi frequency, related to a coupling of the photon mode with a finite-number qubit environment, plays the role of the transition's control parameter. We use the ...

Added: October 29, 2021

Bolshedvorskii S., Vorobyov V., Soshenko V. et al., Optical Materials Express 2017 Vol. 7 No. 11 P. 4038-4049

In this paper, we experimentally investigate optical and spin properties of NV centers in aggregates of detonation nanodiamonds. We show that despite the small size of nanodiamonds forming the aggregate, the NV centers in these aggregates exhibit spin properties comparable to similar size nanodiamonds grown by other methods, but with brightness enhanced by a factor ...

Added: April 28, 2021

Katushkina O. A., Quemerais E., Izmodenov V.V. et al., JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 2017 Vol. 122 No. 11 P. 10921-10937

In this work, we present for the first time the Lyman α intensities measured by Voyager 1/UVS in 2003–2014 (at 90–130 AU from the Sun). During this period Voyager 1 measured the Lyman α emission in the outer heliosphere at an almost fixed direction close to the upwind (i.e.“ toward the interstellar flow). The data show an unexpected behavior in 2003–2009: the ...

Added: January 26, 2018