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We obtain the finite-temperature unconditional master equation of the density matrix for two coupled quantum dots (CQD) when one dot is subjected to a measurement of its electron occupation number using a point contact (PC). To determine…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Hsi-Sheng Goan , G. J. Milburn , H. M. Wiseman , He Bi Sun

We report on the first experimental demonstration of purification of nonclassical continuous variable states. The protocol uses two copies of phase-diffused states overlapped on a beam splitter and provides Gaussified, less mixed states…

Quantum Physics · Physics 2007-07-03 A. Franzen , B. Hage , J. DiGuglielmo , J. Fiurasek , R. Schnabel

We propose a qubit-environment entanglement measure which is tailored for evolutions that lead to pure dephasing of the qubit, such as are abundant in solid state scenarios. The measure can be calculated directly form the density matrix…

Quantum Physics · Physics 2020-10-21 Katarzyna Roszak

We compute the distribution of the purity for random density matrices (i.e.random mixed states) in a large quantum system, distributed according to the Bures measure. The full distribution of the purity is computed using a mapping to random…

Statistical Mechanics · Physics 2015-05-30 Gaëtan Borot , Céline Nadal

A concise and self-contained derivation of hybrid quantum-classical dynamics is given in terms of Markovian master equations. Many previously known results are re-derived, revised, some of them completed or corrected. Using as simple method…

Quantum Physics · Physics 2024-10-23 Lajos Diósi

We investigate signatures of non-Markovianity in the dynamics of a periodically-driven qubit coupled to a dissipative bosonic environment. We propagate the dynamics of the reduced density matrix of the qubit by integrating the numerically…

Quantum Physics · Physics 2024-04-30 Graziano Amati

We present a comprehensive implementation of the quantum trajectory theory for the description of the entanglement dynamics in a Markovian open quantum system made of two qubits. We introduce the average concurrence to characterize the…

Quantum Physics · Physics 2014-11-03 Ivonne Guevara , Carlos Viviescas

A fundamental task in quantum information science is to measure nonlinear functionals of quantum states, such as $\mathrm{Tr}(\rho^k O)$. Intuitively, one expects that computing a $k$-th order quantity generally requires $O(k)$ copies of…

Quantum Physics · Physics 2025-09-03 Yukun Zhang , Yusen Wu , You Zhou , Xiao Yuan

We present a numerical path-integral iteration scheme for the low dimensional reduced density matrix of a time-dependent quantum dissipative system. Our approach simultaneously accounts for the combined action of a microscopically modelled…

Quantum Physics · Physics 2016-10-12 A. M. Barth , A. Vagov , V. M. Axt

Finding controls for open quantum systems needs to take into account effects from unwanted environmental noise. Since actual realizations or states of the noise are typically unknown, the usual treatment for the quantum system's decoherence…

Quantum Physics · Physics 2026-05-12 Wirawat Kokaew , Thiparat Chotibut , Areeya Chantasri

We generalize and extend the stochastic path integral formalism and action principle for continuous quantum measurement introduced in [A. Chantasri, J. Dressel and A. N. Jordan, Phys. Rev. A {\bf 88}, 042110 (2013)], where the optimal…

Quantum Physics · Physics 2015-09-23 Areeya Chantasri , Andrew N. Jordan

Preparing a quantum system in a pure state is ultimately limited by the nature of the system's evolution in the presence of its environment and by the initial state of the environment itself. We show that, when the system and environment…

Quantum Physics · Physics 2015-01-05 Francesco Ticozzi , Lorenza Viola

We present a systematic study of the purity for Gaussian states of single-mode continuous variable systems. We prove the connection of purity to observable quantities for these states, and show that the joint measurement of two conjugate…

Quantum Physics · Physics 2007-05-23 M. G. A. Paris , F. Illuminati , A. Serafini , S. De Siena

Any tripartite state which saturates the strong subadditivity relation for the quantum entropy is defined as the Markov state.A tripartite pure state describing an open system, its environment and their purifying system isa pure Markov…

Quantum Physics · Physics 2016-09-21 A. Türkmen , A. Verçin , S. Yılmaz

A quantum stochastic model for an open dynamical system (quantum receiver) and output multi-channel of observation with an additive nonvacuum quantum noise is given. A quantum stochastic Master equation for the corresponding instrument is…

Quantum Physics · Physics 2015-06-26 V. P. Belavkin

We study the entanglement dynamics of multi-qubit systems coupled to a common dissipative environment, focusing on systems with one or two initially excited qubits. Using the Lindblad master equation, we derive the time evolution of the…

Quantum Physics · Physics 2025-04-15 Z. Bakhshi , E. Morsheddoost , A. Zeynali

We present an efficient algorithm for simulating open quantum systems dynamics described by the Lindblad master equation on quantum computers, addressing key challenges in the field. In contrast to existing approaches, our method achieves…

Quantum Physics · Physics 2024-12-31 Giovanni Di Bartolomeo , Michele Vischi , Tommaso Feri , Angelo Bassi , Sandro Donadi

We study the problem of mapping an unknown mixed quantum state onto a known pure state without the use of unitary transformations. This is achieved with the help of sequential measurements of two non-commuting observables only. We show that…

Quantum Physics · Physics 2009-11-11 L. Roa , M. L. Ladron de Guevara , A. Delgado , A. Klimov

Sampling from a high-dimensional distribution is a fundamental task in statistics, engineering, and the sciences. A canonical approach is the Langevin Algorithm, i.e., the Markov chain for the discretized Langevin Diffusion. This is the…

Statistics Theory · Mathematics 2022-11-01 Jason M. Altschuler , Kunal Talwar

The properties of molecules and materials containing light nuclei are affected by their quantum mechanical nature. Modelling these quantum nuclear effects accurately requires computationally demanding path integral techniques. Considerable…

Chemical Physics · Physics 2020-04-22 Venkat Kapil , David M. Wilkins , Jinggang Lan , Michele Ceriotti