Squeezed Quantum Fluctuations Research Articles

Unconventional Photon Blockade in a Hybrid Optomechanical System with an Embedded Spin‐Triplet

AbstractThis research investigates the unconventional photon blockade in a hybrid optomechanical system with an embedded spin‐triplet state. The self‐homodyning interference between squeezed quantum fluctuations produced by the emitter and the coherent fraction from the driving laser results in two‐photon suppression. Analytical solutions of the correlator equation and numerical simulations of the master equation reveal that modulated mechanical dissipation plays a crucial role in achieving strong single‐photon blockade. In contrast to conventional cavity optomechanical systems, a second‐order correlation function of can be achieved with weak single‐photon optomechanical coupling. By combining unconventional and conventional antibunching, the hybrid system achieves the convergence of maximal photon population, two‐photon interference, and suppression of higher‐order correlations. Additionally, the influence of the thermal noise on photon blockade is investigated, demonstrating greater robustness of the second‐order correlation under weaker phonon‐spin coupling.

Towards Quantum Noise Squeezing for 2-Micron Light with Tellurite and Chalcogenide Fibers with Large Kerr Nonlinearity

Squeezed light—nonclassical multiphoton states with fluctuations in one of the quadrature field components below the vacuum level—has found applications in quantum light spectroscopy, quantum telecommunications, quantum computing, precision quantum metrology, detecting gravitational waves, and biological measurements. At present, quantum noise squeezing with optical fiber systems operating in the range near 1.5 μm has been mastered relatively well, but there are no fiber sources of nonclassical squeezed light beyond this range. Silica fibers are not suitable for strong noise suppression for 2 µm continuous-wave (CW) light since their losses dramatically deteriorate the squeezed state of required lengths longer than 100 m. We propose the generation multiphoton states of 2-micron 10-W class CW light with squeezed quantum fluctuations stronger than −15 dB in chalcogenide and tellurite soft glass fibers with large Kerr nonlinearities. Using a realistic theoretical model, we numerically study squeezing for 2-micron light in step-index soft glass fibers by taking into account Kerr nonlinearity, distributed losses, and inelastic light scattering processes. Quantum noise squeezing stronger than −20 dB is numerically attained for a customized As2Se3 fibers with realistic parameters for the optimal fiber lengths shorter than 1 m. For commercial As2S3 and customized tellurite glass fibers, the expected squeezing in the −20–−15 dB range can be reached for fiber lengths of the order of 1 m.

Formation of Non-Classical Multiphoton States of Light with Squeezed Quantum Fluctuations in Bismuth-Modified Tellurite Glass Fibers

Formation of Non-Classical Multiphoton States of Light with Squeezed Quantum Fluctuations in Bismuth-Modified Tellurite Glass Fibers

Numerical simulation of dispersion and nonlinear characteristics of microstructured silica fibres with a thin suspended core in a wide range of their parameters

Dispersion and nonlinear characteristics of microstructured silica fibres with a thin suspended core surrounded by three, four or six air holes have been studied theoretically in the wavelength range 1 – 2 μm. It has been shown that, owing to strong fundamental mode confinement near the core, the Kerr nonlinearity coefficient can exceed the nonlinearity coefficient of standard telecom fibre SMF28e by two orders of magnitude. The large waveguide contribution allows for effective group velocity dispersion management. Estimates are presented that demonstrate the feasibility of using suspended core fibre exhibiting Kerr nonlinearity for generating non-classical light: a state with squeezed quantum fluctuations in one of the quadrature components of a cw laser signal at a wavelength near 1.55 μm.

Squeezing of cw light in a single-mode dispersive chi (2) medium.

We present a unified analysis of the quantum fluctuations and quadrature squeezing of continuous wave (cw) light propagating in a single-mode quadratic (${\mathrm{\ensuremath{\chi}}}^{(2)}$) waveguide. We retain the effects of wave-vector and group-velocity mismatch, group-velocity dispersion, and depletion by linearizing the quantum fluctuations with respect to the the exact cw nonlinear semiclassical evolution. Each of the characteristic three-wave mixing phenomena, including parametric amplification, second-harmonic generation, and special eigenmode solutions are discussed and contrasted. Regimes of strong squeezing, and the influence of classical parametric modulational instabilities and spatial bifurcations on the spectrum of squeezed quantum fluctuations, are discussed. \textcopyright{} 1996 The American Physical Society.

Physical realization of an environment with squeezed quantum fluctuations via quantum-nondemolition-mediated feedback.

We show how a squeezed environment can be obtained by means of a suitable feedback of the output signal corresponding to a quantum-nondemolition (QND) measurement of an observable. As an example we show how the variance of a field quadrature of a cavity mode subject to QND-mediated feedback can be squeezed below the standard quantum limit and that this actually means that applying feedback is equivalent to coupling the mode to a squeezed environment.

On the SU(1, 1) Phase-space Description of Reduced and Squeezed Quantum Fluctuations

Abstract We derive a phase-space description of squeezed fluctuations using the SU(1, 1) generalized coherent states. We introduce the coherent-diagonal representation of quantum states, based on squeezed coherent states. In this representation we derive generalized Fokker-Planck equations for a quasi-distribution in phase-space formed by SU(1, 1) states. We solve this equation for different representations of the SU(1, 1) group involving as examples parameteric amplifiers and two-mode upconvertors.

Bistability and other effects in a nonlinear fiber-optic ring resonator

Dispersive optical bistability with a threshold cw input power of approximately 10 mW has been observed in a single-mode fiber-optic ring resonator. Light is coupled in and out of the resonator by a single-mode-fiber variable directional coupler. A fiber-optic Faraday isolator is incorporated into the ring, thus increasing the threshold for stimulated Brillouin oscillation by a factor of 100 and permitting other weaker nonlinear effects such as bistability to be observed. Phase-sensitive amplification and deamplification (squeezing) of classical time-stationary noise is demonstrated and shown to be in agreement with the theory of squeezed-state generation in such a nonlinear fiber ring resonator. Light scattering by elastic eigenmodes of the fiber (guided-acoustic-wave Brillouin scattering, GAWBS) adds noise to light circulating in the resonator and obscures the observation of squeezed quantum fluctuations. The properties of this GAWBS scattering are investigated and compared with theory.

Squeezed quantum fluctuations and macroscopic quantum coherence.

Preservation of a macroscopic superposition quantum state is achieved in the presence of dissipation when the quantum fluctuations of the heat bath are squeezed. An example is given for a single mode of the electromagnetic field interacting with a squeezed bath. We show that a squeezed bath is more efficient than a thermal or vacuum bath for optical quadrature-phase measurements, and may also be used to prepare states with low quantum noise in one quadrature phase.

Squeezed Quantum Fluctuations and Noise Limits in Amplifiers and Attenuators

Squeezed Quantum Fluctuations and Noise Limits in Amplifiers and Attenuators

On the Quantum Mechanics of Squeezed States

Abstract We show that the squeezed states of quantum optics are physically and mathematically equivalent to Gaussian wave packets. In the framework of wave mechanics it is possible to formulate and investigate in a very simple way all the properties of reduced or squeezed fluctuations of the position and momentum operators. We study squeezed quantum fluctuations of a minimum-uncertainty Gaussian wave function under two different dynamical conditions of free evolution and harmonic oscillation.

Effect of dissipation on squeezed quantum fluctuations.

The decay of squeezed quantum fluctuations of a system coupled to a dissipative environment is discussed. For a model where the heat bath consists of an infinite set of harmonic oscillators, exact results for the time evolution of the mean-square fluctuations are obtained for arbitrary bath temperature and arbitrary damping strength.