The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
D. F. Walls - One of the best experts on this subject based on the ideXlab platform.
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Quantum-Nondemolition Measurement of photon number using radiation pressure
Physical review. A Atomic molecular and optical physics, 1994Co-Authors: Kurt Jacobs, Paolo Tombesi, Matthew Collett, D. F. WallsAbstract:We propose a quantum-Nondemolition Measurement of the amplitude quadrature and the photon-number statistics by using the effect of radiation pressure on a freely suspended mirror. We propose to measure the momentum fluctuations of the mirror which will give us a readout of the amplitude quadrature fluctuations. The scheme we propose is able to avoid the back-action noise leaving the state of the field after the Measurement practically undegraded.
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Quantum-Nondemolition-Measurement scheme using a Kerr medium.
Physical review. A Atomic molecular and optical physics, 1992Co-Authors: A. N. Chaba, Matthew Collett, D. F. WallsAbstract:In this paper, we present a theoretical study of the quantum-Nondemolition properties of a scheme that uses a Kerr medium in a double-ended cavity with both the signal and the probe inputs being coherent fields incident from the two sides. We find that with a suitable choice of parameters this system satisfies almost perfectly the criteria for quantum-Nondemolition Measurements.
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Nondegenerate two-mode squeezing and quantum-Nondemolition Measurements using three-level atoms in a cavity
Physical review. A Atomic molecular and optical physics, 1992Co-Authors: Matthew Collett, D. F. WallsAbstract:We consider two modes of the electromagnetic field interacting via a three-level atom in a ladder configuration. We calculate the squeezing spectra of the sum and difference of the two output beams. The usefulness of this system as a quantum-Nondemolition-Measurement scheme is analyzed and a prediction is made using the parameters of a recent experiment by Grangier et al. [Phys. Rev. Lett. 66, 1418 (1991)]. We use a full three-level model in the most general case and in particular the influence of both the one-photon and the two-photon detunings are investigated.
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quantum Nondemolition Measurements of photon number by atomic beam deflection
Physical Review Letters, 1991Co-Authors: M J Holland, D. F. Walls, Peter ZollerAbstract:We present a new quantum Nondemolition Measurement scheme in which a measure of the photon statistics of a cavity field can be achieved by monitoring the deflection of atoms interacting with the field. Repeated Measurements result in the collapse of the photon distribution in the field to a number state. Quantum jumps in the photon number are observed when the cavity field is coupled to an external reservoir
Robert Schoelkopf - One of the best experts on this subject based on the ideXlab platform.
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Continuous Quantum Nondemolition Measurement of the Transverse Component of a Qubit.
Physical review letters, 2016Co-Authors: Uri Vool, Shyam Shankar, S.o. Mundhada, Nissim Ofek, Anirudh Narla, K. Sliwa, E. Zalys-geller, Yanhui Liu, Luigi Frunzio, Robert SchoelkopfAbstract:Quantum jumps of a qubit are usually observed between its energy eigenstates, also known as its longitudinal pseudospin component. Is it possible, instead, to observe quantum jumps between the transverse superpositions of these eigenstates? We answer positively by presenting the first continuous quantum Nondemolition Measurement of the transverse component of an individual qubit. In a circuit QED system irradiated by two pump tones, we engineer an effective Hamiltonian whose eigenstates are the transverse qubit states, and a dispersive Measurement of the corresponding operator. Such transverse component Measurements are a useful tool in the driven-dissipative operation engineering toolbox, which is central to quantum simulation and quantum error correction.
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Protocols for optimal readout of qubits using a continuous quantum Nondemolition Measurement
Physical Review A, 2007Co-Authors: Jay M Gambetta, William A Braff, Andreas Wallraff, S M Girvin, Robert SchoelkopfAbstract:We study how the spontaneous relaxation of a qubit affects a continuous quantum Nondemolition Measurement of the initial state of the qubit. Given some noisy Measurement record $\ensuremath{\Psi}$, we seek an estimate of whether the qubit was initially in the ground or excited state. We investigate four different Measurement protocols, three of which use a linear filter (with different weighting factors) and a fourth which uses a full nonlinear filter that gives the theoretically optimal estimate of the initial state of the qubit. We find that relaxation of the qubit at rate $1∕{T}_{1}$ strongly influences the fidelity of any Measurement protocol. To avoid errors due to this decay, the Measurement must be completed in a time that decrease linearly with the desired fidelity while maintaining an adequate signal to noise ratio. We find that for the nonlinear filter the predicted fidelity, as expected, is always better than the linear filters and that the fidelity is a monotone increasing function of the Measurement time. For example, to achieve a fidelity of 90%, the box car linear filter requires a signal to noise ratio of $\ensuremath{\sim}30$ in a time ${T}_{1}$, whereas the nonlinear filter only requires a signal to noise ratio of $\ensuremath{\sim}18$.
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protocols for optimal readout of qubits using a continuous quantum Nondemolition Measurement
Physical Review A, 2007Co-Authors: Jay M Gambetta, William A Braff, Andreas Wallraff, S M Girvin, Robert SchoelkopfAbstract:We study how the spontaneous relaxation of a qubit affects a continuous quantum Nondemolition Measurement of the initial state of the qubit. Given some noisy Measurement record {psi}, we seek an estimate of whether the qubit was initially in the ground or excited state. We investigate four different Measurement protocols, three of which use a linear filter (with different weighting factors) and a fourth which uses a full nonlinear filter that gives the theoretically optimal estimate of the initial state of the qubit. We find that relaxation of the qubit at rate 1/T{sub 1} strongly influences the fidelity of any Measurement protocol. To avoid errors due to this decay, the Measurement must be completed in a time that decrease linearly with the desired fidelity while maintaining an adequate signal to noise ratio. We find that for the nonlinear filter the predicted fidelity, as expected, is always better than the linear filters and that the fidelity is a monotone increasing function of the Measurement time. For example, to achieve a fidelity of 90%, the box car linear filter requires a signal to noise ratio of {approx}30 in a time T{sub 1}, whereas the nonlinear filter only requires a signal to noisemore » ratio of {approx}18.« less
Masataka Shirasaki - One of the best experts on this subject based on the ideXlab platform.
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Noise reduction in quantum Nondemolition Measurement with a nonlinear Mach–Zehnder interferometer using squeezed vacuum
Journal of the Optical Society of America B, 1991Co-Authors: Masataka Shirasaki, Hermann A. HausAbstract:A quantum Nondemolition Measurement of photon number taken with a nonlinear Mach–Zehnder interferometer is analyzed. When this interferometer is excited by a coherent input, it shows a large amount of noise, caused by the self-phase modulation. We demonstrate how this noise can be suppressed by applying a squeezed vacuum to the unexcited port of the interferometer.
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noise reduction in quantum Nondemolition Measurement with a nonlinear mach zehnder interferometer using squeezed vacuum
Journal of The Optical Society of America B-optical Physics, 1991Co-Authors: Masataka Shirasaki, H A HausAbstract:A quantum Nondemolition Measurement of photon number taken with a nonlinear Mach–Zehnder interferometer is analyzed. When this interferometer is excited by a coherent input, it shows a large amount of noise, caused by the self-phase modulation. We demonstrate how this noise can be suppressed by applying a squeezed vacuum to the unexcited port of the interferometer.
Valeriy V. Yashchuk - One of the best experts on this subject based on the ideXlab platform.
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AC Stark shift noise in QND Measurement arising from quantum fluctuations of light polarization
eScholarship University of California, 2018Co-Authors: Auzinsh M, Jason Stalnaker, Alexander O. Sushkov, Budker D, Df Kimball, Sm Rochester, Valeriy V. YashchukAbstract:In a recent letter [Auzinsh {\it{et. al.}} (physics/0403097)] we have analyzed the noise properties of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum Nondemolition Measurement. Such a magnetometer measures spin precession of $N$ atomic spins by detecting optical rotation of far-detuned probe light. Here we consider maximally squeezed probe light, and carry out a detailed derivation of the contribution to the noise in a magnetometric Measurement due to the differential AC Stark shift between Zeeman sublevels arising from quantum fluctuations of the probe polarization
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Can a quantum Nondemolition Measurement improve the sensitivity of an atomic magnetometer
Physical review letters, 2004Co-Authors: Marcis Auzinsh, Dmitry Budker, Derek F. Jackson Kimball, Simon M. Rochester, Jason Stalnaker, Alexander O. Sushkov, Valeriy V. YashchukAbstract:We consider the limitations due to noise (e.g., quantum projection noise and photon shot-noise) on the sensitivity of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum Nondemolition Measurement. Such a magnetometer measures spin precession of N atomic spins by detecting optical rotation of far-detuned light. We show that for very short Measurement times, the optimal sensitivity scales as N(-3/4); if strongly squeezed probe light is used, the Heisenberg limit of N-1 scaling can be achieved. However, if the Measurement time exceeds tau(rel)/N(1/2) in the former case, or tau(rel)/N in the latter, where tau(rel) is the spin relaxation time, the scaling becomes N(-1/2), as for a standard shot-noise-limited magnetometer.
V. P. Belavkin - One of the best experts on this subject based on the ideXlab platform.
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the Nondemolition Measurement of quantum time
arXiv: Quantum Physics, 2005Co-Authors: V. P. Belavkin, M G PerkinsAbstract:The problem of time operator in quantum mechanics is revisited. The unsharp Measurement model for quantum time based on the dynamical system-clock interaction, is studied. Our analysis shows that the problem of the quantum time operator with continuous spectrum cannot be separated from the Measurement problem for quantum time.
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Nondemolition principle of quantum Measurement theory
arXiv: Quantum Physics, 2005Co-Authors: V. P. BelavkinAbstract:We give an explicit axiomatic formulation of the quantum Measurement theory which is free of the projection postulate. It is based on the generalized Nondemolition principle applicable also to the unsharp, continuous-spectrum and continuous-in-time observations. The "collapsed state-vector" after the "objectification" is simply treated as a random vector of the a posteriori state given by the quantum filtering, i.e., the conditioning of the a priori induced state on the corresponding reduced algebra. The nonlinear phenomenological equation of "continuous spontaneous localization" has been derived from the Schroedinger equation as a case of the quantum filtering equation for the diffusive Nondemolition Measurement. The quantum theory of Measurement and filtering suggests also another type of the stochastic equation for the dynamical theory of continuous reduction, corresponding to the counting Nondemolition Measurement, which is more relevant for the quantum experiments.
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a new wave equation for a continuous Nondemolition Measurement
arXiv: Quantum Physics, 2005Co-Authors: V. P. BelavkinAbstract:A stochastic model for Nondemolition continuous Measurement in a quantum system is given. It is shown that the posterior dynamics, including a continuous collapse of the wave function, is described by a nonlinear stochastic wave equation. For a particle in an electromagnetic field it reduces the Schroedinger equation with extra imaginary stochastic potentials.
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Nondemolition principle of quantum Measurement theory
Foundations of Physics, 1994Co-Authors: V. P. BelavkinAbstract:We give an explicit axiomatic formulation of the quantum Measurement theory which is free of the projection postulate. It is based on the generalized Nondemolition principle applicable also to the unsharp, continuous-spectrum and continuous-in-time observations. The “collapsed state-vector” after the “objectification” is simply treated as a random vector of the a posteriori state given by the quantum filtering, i.e., the conditioning of the a priori induced state on the corresponding reduced algebra. The nonlinear phenomenological equation of “continuous spontaneous localization” has been derived from the Schrödinger equation as a case of the quantum filtering equation for the diffusive Nondemolition Measurement. The quantum theory of Measurement and filtering suggests also another type of the stochastic equation for the dynamical theory of continuous reduction, corresponding to the counting Nondemolition Measurement, which is more relevant for the quantum experiments .
