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Register a new userA simple approach to the quantum theory of nonlinear fiber optics
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We put forth an approach to obtain a quantum master equation for the propagation of light in nonlinear fiber optics by relying on simple quantum pictures of the processes (linear and nonlinear) occurring along propagation in an optical fiber. This equation is shown to be in excellent agreement with the classical Generalized Nonlinear Schrodinger Equation and predicts the effects of self-steepening and spontaneous Raman scattering. Last, we apply these results to the analysis of two cases of relevance in quantum technologies: single-photon frequency translation and spontaneous four-wave mixing.
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We analyze the amplification processes occurring in a nonlinear fiber, either driven with one or two pumps. After determining the solution for the signal and idler fields resulting from these amplification processes, we analyze the physical transformations that these fields undergo. To this aim, we use a Bloch-Messiah decomposition for the symplectic transformation governing the fields evolution. Although conceptually equivalent to other works in this area [McKinstrie and Karlsson, Opt. Expr. 21, 1374 (2013)], this analysis is intended to be particularly simple, gathering results spread in the literature, which is useful for guiding practical implementations. Furthermore, we present a study of the correlations of the signal-idler fields at the amplifier output. We show that these fields are correlated, study their correlations as a function of the pump power, and stress the impact of these correlations on the amplifier noise figure. Finally, we address the effect of losses. We determine whether it is advantageous to consider a link consisting in an amplifying non-linear fiber, followed by a standard fiber based lossy transmission line, or whether the two elements should be reversed, by comparing the respective noise figures.
We investigate the interaction between light and molecular systems modeled as quantum emitters coupled to a multitude of vibrational modes via a Holstein-type interaction. We follow a quantum Langevin equations approach that allows for analytical derivations of absorption and fluorescence profiles of molecules driven by classical fields or coupled to quantized optical modes. We retrieve analytical expressions for the modification of the radiative emission branching ratio in the Purcell regime and for the asymmetric cavity transmission associated with dissipative cross-talk between upper and lower polaritons in the strong coupling regime. We also characterize the F{o}rster resonance energy transfer process between donor-acceptor molecules mediated by the vacuum or by a cavity mode.
This is a pre-publication version of a forthcoming book on quantum atom optics. It is written as a senior undergraduate to junior graduate level textbook, assuming knowledge of basic quantum mechanics, and covers the basic principles of neutral atom matter wave systems with an emphasis on quantum technology applications. The topics covered include: introduction to second quantization of many-body systems, Bose-Einstein condensation, the order parameter and Gross-Pitaevskii equation, spin dynamics of atoms, spinor Bose-Einstein condensates, atom diffraction, atomic interferometry beyond the standard limit, quantum simulation, squeezing and entanglement with atomic ensembles, quantum information with atomic ensembles. This book would suit students who wish to obtain the necessary skills for working with neutral atom many-body atomic systems, or could be used as a text for an undergraduate or graduate level course (exercises are included throughout). This is a near-final draft of the book, but inevitably errors may be present. If any errors are found, we welcome you to contact us and it will be corrected before publication. (TB: tim.byrnes[at]nyu.edu, EI: ebube[at]nyu.edu)
We demonstrate that there exists a universal, near-optimal recovery map---the transpose channel---for approximate quantum error-correcting codes, where optimality is defined using the worst-case fidelity. Using the transpose channel, we provide an alternative interpretation of the standard quantum error correction (QEC) conditions, and generalize them to a set of conditions for approximate QEC (AQEC) codes. This forms the basis of a simple algorithm for finding AQEC codes. Our analytical approach is a departure from earlier work relying on exhaustive numerical search for the optimal recovery map, with optimality defined based on entanglement fidelity. For the practically useful case of codes encoding a single qubit of information, our algorithm is particularly easy to implement.
Since the very early days of quantum theory there have been numerous attempts to interpret quantum mechanics as a statistical theory. This is equivalent to describing quantum states and ensembles together with their dynamics entirely in terms of phase-space distributions. Finite dimensional systems have historically been an issue. In recent works [Phys. Rev. Lett. 117, 180401 and Phys. Rev. A 96, 022117] we presented a framework for representing any quantum state as a complete continuous Wigner function. Here we extend this work to its partner function -- the Weyl function. In doing so we complete the phase-space formulation of quantum mechanics -- extending work by Wigner, Weyl, Moyal, and others to any quantum system. This work is structured in three parts. Firstly we provide a brief modernized discussion of the general framework of phase-space quantum mechanics. We extend previous work and show how this leads to a framework that can describe any system in phase space -- putting it for the first time on a truly equal footing to Schrodingers and Heisenbergs formulation of quantum mechanics. Importantly, we do this in a way that respects the unifying principles of parity and displacement in a natural broadening of previously developed phase space concepts and methods. Secondly we consider how this framework is realized for different quantum systems; in particular we consider the proper construction of Weyl functions for some example finite dimensional systems. Finally we relate the Wigner and Weyl distributions to statistical properties of any quantum system or set of systems.
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