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A. E. Teretenkov

Publications and source records attributed to A. E. Teretenkov.

At least 19 recordsLinked to original sources
arXiv2026

Hidden collision statistics in bosonic heat transport: Superthermal correlations at fixed mean current

Reservoirs with the same mean relaxation rate can be indistinguishable at the level of average energy transport while producing different fluctuations. We study a bosonic mode coupled to hot and cold Poisson streams of thermal ancillas through finite beam-splitter collisions. The averaged evolution is a compound-Poisson semigroup generated by finite Gaussian event channels. Its nonequilibrium steady state is an exact mixture of thermal states governed by a random affine fixed point. Consequently, the mean-occupation dynamics and bath-resolved mean heat currents coincide with those of the matched continuous Lindblad reservoir, whereas higher correlations retain the collision strength. For equal collision transmissivities, we derive an exact superthermal bunching law controlled by the temperature contrast and collision strength. We also obtain the asymptotic rates of the first two heat cumulants for an ideal stationary event-resolved two-point-measurement record and separate local one-collision contributions from temporal correlations. Fock-space diagonalization and Monte Carlo trajectories validate the formulas and connect full resets to the weak-collision Gaussian limit.

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arXiv2026

Constructing Fermionic Dynamics with Closed Moment Hierarchies

We construct a broad class of completely positive maps and Gorini-Kossakowski-Sudarshan-Lindblad generators for fermionic systems induced by linear transformations of system and environment modes. For these maps, we derive explicit Heisenberg-picture formulas for arbitrary normally ordered monomials in terms of minors of the underlying mode-transformation matrices and environment correlation tensors. We show that for even environment states the linear span of monomials up to any fixed order is invariant, which yields closed equations for low-order moments and makes their computation efficient. We also discuss the relation of this construction to second quantization of non-Hermitian one-particle contractions and extend the formalism to completely positive maps arising from post-selection.

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arXiv2025

Gaussian approximation and its corrections for driven dissipative Kerr model

We develop a systematic projection-operator technique for constructing Gaussian approximations and their perturbative corrections in bosonic nonlinear models. As a case study, we apply it to the driven dissipative Kerr oscillator. In the absence of external driving, the model can be solved exactly within a low-dimensional Fock subspace, leading to strongly non-Gaussian states. Nevertheless, we demonstrate that the evolution of first- and second-order moments is captured by our Gaussian scheme with high accuracy even in this regime, providing a natural benchmark. For the general case with external driving, our approach reduces the equations of motion to a closed system for means and covariances and allows one to compute systematic corrections beyond the Gaussian level in closed form. We also calculate the dynamics of linear and quadratic combinations of creation and annihilation operators in both weak- and strong-drive regimes.

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arXiv2025

Sub-Poissonian Light in a Waveguide Kerr-medium

Waveguides on a chip represent a new medium for implementing nonlinear optical transformations of light. Modern $\text{Si}_3\text{N}_4$ chip waveguides are attractive due to their high Kerr nonlinearity, suppressed Brillouin scattering on guided acoustic waves (GAWBS), and lengths up to one meter. The capabilities of waveguides for generating sub-Poissonian light in the form of a displaced Kerr state are analyzed. We offer new analytical formulas for estimating the capabilities of suppressing photon fluctuations of a displaced Kerr state for any value of input light amplitude. The results of numerical calculations are presented. It is shown that the degree of photon noise suppression can reach values of 5 - 15 dB with 100 mW light power in waveguides a few meters long.

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arXiv2025

Long-time behavior of multi-level open systems interacting with non-vacuum reservoirs

The model of multi-level open quantum system interacting with a non-vacuum reservoir in the rotating wave approximation is considered. We provide an exact integral representation for the reduced density matrix of the system. For identical uncorrelated reservoirs in diagonal states, we have obtained the first perturbative correction for such dynamics in the Bogolubov-van Hove limit. We have shown that after initial state renormalization, it can be completely described in terms of finite-dimensional semigroup. The method we provide can also be applied to the further orders of perturbation theory with Bogolubov-van Hove scaling.

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arXiv2025

Repeated temperature measurements in quantum thermodynamics

In this work, we model the temperature measurement as a transformation of the arbitrary state into the Gibbs state. We start with a general formalism of ansatz-posteriors, which includes many usual models of posterior states due to measurement or state preparation. On the one hand, it contains models of selective and non-selective measurements posteriors as special cases, which allows us to consider it as a generalization of usual measurement models. On the other hand, it contains the above mentioned transformation into the Gibbs state as a special case as well. We derive an analogue of the master equation in the stroboscopic limit of repeated measurements. Then we apply our general approach to temperature measurement.

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arXiv2025

Parametric approximation as open quantum systems problem

In this work we develop an open quantum system view of the parametric approximation, which allows us to obtain systematic perturbative corrections to it. We consider the Jaynes-Cummings model with dissipation, assuming that the field is in the regime close to the parametric approximation with depletion. We obtain non-unitary corrections to the parametric approximation and additional dynamical Lamb-shift contributions to it. For high detuning, these non-unitary corrections appear to be non-Markovian before depletion. And we show that even after depletion, initial non-Markovian behaviour contributes to the dynamics via laser-induced polishing of the density matrix.

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arXiv2024

Superoperator master equations for depolarizing dynamics

The work is devoted to superoperator master equations. Namely, the superoperator master equations in the case of the twirling hyperprojector with respect to the whole unitary group are derived. To be consistent with such a hyperprojector the free dynamics is assumed to be depolarizing. And it is perturbed by the arbitrary Gorini--Kossakowski--Sudarshan--Lindblad generator. The explicit form of the second order master equations are presented in this case.

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arXiv2023

On time-dependent projectors and on generalization of thermodynamical approach to open quantum systems

In this paper, we develop a consistent perturbative technique for obtaining a time-local master equation based on projective methods in the case where the projector depends on time. We then introduce a generalization of the Kawasaki--Gunton projector, which allows us to use this technique to derive, generally speaking, nonlinear master equations in the case of arbitrary ansatzes consistent with some set of observables. Most of our results are very general, but in our discussion we focus on the application of these results to the theory of open quantum systems.

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arXiv2023

Time-convolutionless master equations for composite open quantum systems

In this work we consider the master equations for composite open quantum systems. We provide purely algebraic formulae for terms of perturbation series defining such equations. We also give conditions under which the Bogolubov-van Hove limit exists and discuss some corrections to this limit. We present an example to illustrate our results. In particular, this example shows, that inhomogeneous terms in time-convolutionless master equations can vanish after reservoir correlation time, but lead to renormalization of initial conditions at such a timescale.

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arXiv2022

Effective Gibbs state for averaged observables

We consider the effective Gibbs state for averaged observables. In particular, we perturbatively calculate the correspondent effective Hamiltonian. We show that there are a lot of similarities between this effective Hamiltonian and the mean force Hamiltonian. We also discuss a thermodynamic role of the information loss due to restriction of our measurement capabilities to such averaged observables.

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arXiv2022

Higher order moments dynamics for some multimode quantum master equations

We derive Heisenberg equations for arbitrary high order moments of creation and annihilation operators in the case of the quantum master equation with a multimode generator which is quadratic in creation and annihilation operators and obtain their solutions. Based on them we also derive similar equations for the case of the quantum master equation, which occur after averaging the dynamics with a quadratic generator with respect to the classical Poisson process. This allows us to show that dynamics of arbitrary finite-order moments of creation and annihilation operators is fully defined by finite number of linear differential equations in this case.

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arXiv2022

Effective Heisenberg equations for quadratic Hamiltonians

We discuss effective quantum dynamics obtained by averaging projector with respect to free dynamics. For unitary dynamics generated by quadratic fermionic Hamiltonians we obtain effective Heisenberg dynamics. By perturbative expansions we obtain the correspondent effective time-local Heisenberg equations. We also discuss a similar problem for bosonic case.

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arXiv2021

Non-perturbative effects in corrections to quantum master equation arising in Bogolubov-van Hove limit

We study the perturbative corrections to the { Gorini-Kossakowski-Sudarshan-Lindblad equation which arises in the weak coupling limit}. The spin-boson model in the rotating wave approximation at zero temperature is considered. We show that the perturbative part of the density matrix satisfies the time-independent Gorini-Kossakowski-Sudarshan-Lindblad equation for arbitrary order of the perturbation theory (if all the moments of the reservoir correlation function are finite). But to reproduce the right asymptotic precision at long times, one should use { an initial condition different} from the one for exact dynamics. Moreover, we show that the initial condition for this master equation even fails to be a density matrix under certain resonance conditions.

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arXiv2021

Long-time Markovianity of multi-level systems in the rotating wave approximation

For the model of a multi-level system in the rotating wave approximation we obtain the corrections for a usual weak coupling limit dynamics by means of perturbation theory with Bogolubov-van Hove scaling. It generalizes our previous results on a spin-boson model in the rotating wave approximation. Additionally, in this work we take into account some dependence of the system Hamiltonian on the small parameter. We show that the dynamics is long-time Markovian, i.e. after the bath correlation time all the non-Markovianity could be captured by the renormalization of initial condition and correlation functions.

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arXiv2020

One-particle approximation as a simple playground for irreversible quantum evolution

Both quantum information features and irreversible quantum evolution of the models arising in physical systems in one-particle approximation are discussed. It is shown that the calculation of the reduced density matrix and entanglement analysis are considerably simplified in this case. The irreversible quantum evolution described by Gorini--Kossakowski--Sudarshan--Lindblad equations in the one-particle approximation could be defined by a solution of a Shroedinger equation with a dissipative generator. It simplifies the solution of the initial equation on the one side and gives a physical interpretation of such a Shroedinger equation with non-Hermitian Hamiltonian on the other side.

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