Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

European Quantum Electronics Conference (EQEC)

Stochastic simulations of dissipation in quantum optics: quantum superpositions

B. M. Garraway, P. L. Knight

Published Aug 24, 2005• 0 citations
Publisher

Abstract

We show how nonclassical states can be constructed by interference amongst constituents in a superposition of basis states (chosen either from a Fock or coherent state basis). Such superpositions are fragile and highly susceptible to dissipation. We discuss the connection between ensemble averages and the evolution of individual realizations using quantum jump and quantum state diffusion models of conditioned measurements, each realization reflecting a particular measurement record. This allows us to distinguish between decoherence, localization and the deconstruction of superpositions into their components.

DOI
10.1109/eqec.1994.698343

Related papers

Generation and Preservation of Coherence in Dissipative Quantum Optical Environments

B. M. Garraway, P. L. Knight, Martin Bodo Plenio

We discuss the decay and decoherence of nonclassical states in quantum optics coupled to zero-temperature heat baths, and contrast ensemble behaviour with that of individual realizations. We show how nonclassical states are highly sensitive to dissipation in a number of cases, but present an example of how dissipation can be used to generate nonclassical states.

Physica Scripta•Jan 1, 1998•13 citations

Quantum Fluctuations in Optical Systems

P. L. Knight

Contents 1 Introduction 2 2 Quantum Interference and the Construction of Nonclassical States 3 2.1 Nonclassical Light, Quadratures and Phase--Sensitive Observables 3 2.2 Phase--Space and Quasi--Probabilities . . . . . . . . . . . . . . . . 13 2.3 Quantum Noise as a Stochastic Process . . . . . . . . . . . . . . 15 2.4 Marginal distributions and reconstruction of Wigner functions . . 18 2.5 Joint Measurements of p, q in Phase Space . . . . . . . . . . . . . 20 2.6 Phase--Space Sampling Entropies . . . . . . . . . . . . . . . . . . 27 2.7 Mutual Information and Entropic Uncertainty . . . . . . . . . . . 28 2.8 Building Nonclassical States by Quantum Interference . . . . . . 30 3 Dissipation Versus Coherent Evolution: Decoherence 36 4 Unravelling the Master Equation 37 5 Quantum Jumps 43 5.1 Intrinsic or Extrinsic Jumps . . . . . . . . . . . . . . . . . . . . . 43 5.2 Observation of Quantum Jumps . . . . . . . . . . . . . .

•Jan 1, 1997•9 citations

Quantum superpositions in dissipative environments: decoherence and deconstruction

P. L. Knight, B. M. Garraway

This chapter describes how the nonclassical states are peculiarly sensitive to dissipation when the coupling of the field modes to their larger environment is taken into account. Well before the field energy is significantly dissipated, the coherences responsible for the nonclassical behaviour will decay, at a ‘decoherence rate’ determined by the square of the separation of the constituent components of the nonclassical superpositions in phase-space. The Wigner functions for each Fock state component are given by Laguerre polynomials. These interfere to generate the superposition of interest. Coherences are destroyed at a rate which is proportional to the degree of excitation of the system as the system relaxes to a statistical mixture of relevant ‘pointer bases’. The chapter shows how the dissipative environment ‘deconstructs’ the field into its appropriate constituent parts. The chapter examines the Jaynes-Cummings system governed by the Milburn equation and shows how the intrinsic decoherence modifies the time evolution of the atomic inversion.

CRC Press eBooks•Dec 12, 2020•4 citations

Quantum superpositions and Schrödinger cat states in quantum optics

Christopher C. Gerry, P. L. Knight

We describe the properties of a quantum system prepared in superpositions of classically distinguishable states. These states, often called Schrödinger cat states, are of great interest at present. We discuss how they may be realized in quantum optics using nonlinear interactions and cavity quantum electrodynamics. We first describe the quantum properties of field states in a cavity, and demonstrate the interference properties which characterize superposition states and discuss how fragile they are in dissipative environments. Finally, we review current experimental approaches which may realize these states.

American Journal of Physics•Oct 1, 1997•152 citations

The quantum-jump approach to dissipative dynamics in quantum optics

Martin Bodo Plenio, P. L. Knight

Dissipation, the irreversible loss of energy and coherence, from a microsystem is the result of coupling to a much larger macrosystem (or reservoir) that is so large that one has no chance of keeping track of all of its degrees of freedom. The microsystem evolution is then described by tracing over the reservoir states, which results in an irreversible decay as excitation leaks out of the initially excited microsystems into the outer reservoir environment. Earlier treatments of this dissipation used density matrices to describe an ensemble of microsystems, either in the Schr\"odinger picture with master equations, or in the Heisenberg picture with Langevin equations. The development of experimental techniques to study single quantum systems (for example, single trapped ions, or cavity-radiation-field modes) has stimulated the construction of theoretical methods to describe individual realizations conditioned on a particular observation record of the decay channel. These methods, variously described as quantum-jump, Monte Carlo wave function, and quantum-trajectory methods, are the subject of this review article. We discuss their derivation, apply them to a number of current problems in quantum optics, and relate them to ensemble descriptions.

arXiv:quant-ph/9702007•Reviews of Modern Physics•Jan 1, 1998•1,514 citations

The quantum mechanics of experiments

Jürg Fröhlich, Alessandro Pizzo

This note starts with a recapitulation of what people call the ``Measurement Problem'' of Quantum Mechanics (QM). The dissipative nature of the quantum-mechanical time-evolution of averages of states over large ensembles of identical isolated systems consisting of matter interacting with the radiation field is discussed and shown to correspond to a stochastic time-evolution of states of individual systems. The importance of dissipation for the successful completion of measurements is highlighted. To conclude, a solution of the ``Measurement Problem'' is sketched in an idealized model of a double-slit experiment.

quant-pharXiv:2603.25335•Mar 27, 2026•0 citations
We show how nonclassical states can be constructed by interference amongst constituents in a superposition of basis states (chosen either from a Fock or coherent state basis). Such superpositions are fragile and highly susceptible to dissipation. We discuss the connection between ensemble averages and the evolution of individual realizations using quantum jump and quantum state diffusion models of conditioned measurements, each realization reflecting a particular measurement record. This allows us to distinguish between decoherence, localization and the deconstruction of superpositions into their components.
Contents 1 Introduction 2 2 Quantum Interference and the Construction of Nonclassical States 3 2.1 Nonclassical Light, Quadratures and Phase--Sensitive Observables 3 2.2 Phase--Space and Quasi--Probabilities . . . . . . . . . . . . . . . . 13 2.3 Quantum Noise as a Stochastic Process . . . . . . . . . . . . . . 15 2.4 Marginal distributions and reconstruction of Wigner functions . . 18 2.5 Joint Measurements of p, q in Phase Space . . . . . . . . . . . . . 20 2.6 Phase--Space Sampling Entropies . . . . . . . . . . . . . . . . . . 27 2.7 Mutual Information and Entropic Uncertainty . . . . . . . . . . . 28 2.8 Building Nonclassical States by Quantum Interference . . . . . . 30 3 Dissipation Versus Coherent Evolution: Decoherence 36 4 Unravelling the Master Equation 37 5 Quantum Jumps 43 5.1 Intrinsic or Extrinsic Jumps . . . . . . . . . . . . . . . . . . . . . 43 5.2 Observation of Quantum Jumps . . . . . . . . . . . . . .
This chapter describes how the nonclassical states are peculiarly sensitive to dissipation when the coupling of the field modes to their larger environment is taken into account. Well before the field energy is significantly dissipated, the coherences responsible for the nonclassical behaviour will decay, at a ‘decoherence rate’ determined by the square of the separation of the constituent components of the nonclassical superpositions in phase-space. The Wigner functions for each Fock state component are given by Laguerre polynomials. These interfere to generate the superposition of interest. Coherences are destroyed at a rate which is proportional to the degree of excitation of the system as the system relaxes to a statistical mixture of relevant ‘pointer bases’. The chapter shows how the dissipative environment ‘deconstructs’ the field into its appropriate constituent parts. The chapter examines the Jaynes-Cummings system governed by the Milburn equation and shows how the intrinsic decoherence modifies the time evolution of the atomic inversion.
We describe the properties of a quantum system prepared in superpositions of classically distinguishable states. These states, often called Schrödinger cat states, are of great interest at present. We discuss how they may be realized in quantum optics using nonlinear interactions and cavity quantum electrodynamics. We first describe the quantum properties of field states in a cavity, and demonstrate the interference properties which characterize superposition states and discuss how fragile they are in dissipative environments. Finally, we review current experimental approaches which may realize these states.
Dissipation, the irreversible loss of energy and coherence, from a microsystem is the result of coupling to a much larger macrosystem (or reservoir) that is so large that one has no chance of keeping track of all of its degrees of freedom. The microsystem evolution is then described by tracing over the reservoir states, which results in an irreversible decay as excitation leaks out of the initially excited microsystems into the outer reservoir environment. Earlier treatments of this dissipation used density matrices to describe an ensemble of microsystems, either in the Schr\"odinger picture with master equations, or in the Heisenberg picture with Langevin equations. The development of experimental techniques to study single quantum systems (for example, single trapped ions, or cavity-radiation-field modes) has stimulated the construction of theoretical methods to describe individual realizations conditioned on a particular observation record of the decay channel. These methods, variously described as quantum-jump, Monte Carlo wave function, and quantum-trajectory methods, are the subject of this review article. We discuss their derivation, apply them to a number of current problems in quantum optics, and relate them to ensemble descriptions.
This note starts with a recapitulation of what people call the ``Measurement Problem'' of Quantum Mechanics (QM). The dissipative nature of the quantum-mechanical time-evolution of averages of states over large ensembles of identical isolated systems consisting of matter interacting with the radiation field is discussed and shown to correspond to a stochastic time-evolution of states of individual systems. The importance of dissipation for the successful completion of measurements is highlighted. To conclude, a solution of the ``Measurement Problem'' is sketched in an idealized model of a double-slit experiment.