Dissipative Cavity Research Articles

Dynamics and protecting of entanglement in two-level systems interacting with a dissipative cavity: the Gardiner–Collett approach

In this paper, we study the exact entanglement dynamics of two two-level atoms in a dissipative cavity. We use the Gardiner–Collett Hamiltonian to model the dissipative cavity, in which we assume that the two atoms resonantly interact with the cavity field and the cavity field itself interacts with the surrounding medium. Then, with the help of the Fano’s technique we show that this system can be regarded as two atoms interacting with a heat bath. In such a case, we find that there exists a decoherence-free state that does not evolve in time. At this time there exists a so-called super-radiant state which decays in time due to dissipation. At last, we use the quantum Zeno effect to preserve the entanglement which already has been stored in the system.

A novel approach to entanglement dynamics of two two-level atoms interacting with dissipative cavities

In this paper, we first introduce a system consisting of two dissipative cavities in which there exists a two-level atom in each cavity. The correlation between these two separate cavities is governed via the field-field interaction term. To describe the dissipation in the cavities we use the approach of the Gardiner-Collett model. By applying two successive suitable canonical transformations, and with the help of the Fano's technique, we simplify the obtained Hamiltonian. After that, the exact analytical solution of the wave function of the considered system is obtained by using the Laplace transform technique. We investigate the dynamics of entanglement for both atom-field weak and strong couplings corresponding to the bad and good cavity limits showing that the field-field coupling constant and the detuning parameter have a significant influence on the entanglement between the two atoms. Finally, we investigate the non-classical properties of the cavity fields by evaluating sub-Poissonian statistics and two-mode squeezing criteria.

Implementation of quantum state manipulation in a dissipative cavity.

We discuss a method to perform dissipation-assisted quantum state manipulation in a cavity. We show that atomic spontaneous emission and cavity decay might be exploited to drive many atoms into many-body steady-state entanglement. Our protocol offers a dramatic improvement in fidelity when noise strength increases. Moreover, the dephasing noise is suppressed effectively by showing that high-fidelity target state can be obtained in a dissipative environment.

Stability and Intrinsic Fluctuations of Dissipative Cavity Solitons in Kerr Frequency Microcombs

The generation of dissipative cavity solitons is one of the most intriguing features of microresonator-based Kerr frequency combs, enabling effective mode locking of comb modes and synthesis of ultrafast pulses. With the Lugiato–Lefever model, here, we conduct detailed theoretical investigations on the transient dynamics of dissipative cavity solitons and describe how several intrinsic effects of the Kerr comb disturb the stability of cavity solitons, including soliton breathing, higher order dispersion, dispersive wave emission, and cavity mode coupling. Our results and analysis agree well with recent measurements and provide insight into some as yet unexplained observations.

Atom-mirror entanglement via cavity dissipation

We present a cavity dissipation scheme to prepare a hybrid system of an atomic ensemble and a moving mirror in squeezed and entangled states. This scheme is based on four-wave mixing in the atoms and radiation pressure on the mirror, both of which combine to lead to Bogoliubov interactions of the atoms and the mirror with the cavity fields. Under adiabatic conditions, the cavity fields cause the hybrid Bogoliubov modes to evolve into the vacuum states, which correspond to the two-mode squeezed and entangled states. The dependence of the hybrid entanglement on the system parameters is also presented in and beyond the Bogoliubov interactions.

Entanglement of Optical and Mechanical Modes Enhanced in Distant Optomechanical Systems by Atomic Coherence

We present a scheme for three-level cascade atoms to entangle various optical and mechanical modes of two coupled cavity optomechanical system. With the existence of atomic mediums, our study shows that the larger stationary macroscopic entanglement of distant optomechanical systems can be obtained and reaches the maximum at the same effective detuning. Furthermore, we find that it is insensitive to the cavity decay rate for the entanglement between the two distant movable mirrors, and between the mirror and the adjacent or the distant cavity mode, which compensates for the effects of the cavity dissipation.

High-Qoperation of superconducting rf cavities: Potential impact of thermocurrents on the rf surface resistance

For many new accelerator applications, superconducting radio frequency (SRF) systems are the enabling technology. In particular for CW applications, much effort is being expended to minimize the power dissipation (surface resistance) of niobium cavities. Starting in 2009, we suggested a means of reducing the residual resistance by performing a thermal cycle [1], a procedure of warming up a cavity after initial cooldown to about 20K and cooling it down again. In subsequent studies [2], this technique was used to manipulate the residual resistance by more than a factor of 2. It was postulated that thermocurrents during cooldown generate additional trapped magnetic flux that impacts the cavity quality factor. Here, we present a more extensive study that includes measurements of two additional passband modes and that confirms the effect. In this paper, we also discuss simulations that support the claim. While the layout of the cavity LHe tank system is cylindrically symmetric, we show that the temperature dependence of the material parameters results in a non-symmetric current distribution. Hence a significant amount of magnetic flux can be generated at the RF surface.

Formation and Energy Exchange of Vector Dark Solitons in Fiber Lasers

The mutual energy-exchange interactions in two orthogonally polarized components of vector dark soliton, which is automatically formed in a normal-dispersion fiber laser cavity in the presence of reverse saturable absorption, and dissipative cavity effects, had been theoretically and numerically investigated. Under specific cavity parameters, a vector dark soliton with periodic coherent energy exchange could be formed and well described by a semianalytic method. The multiple vector dark solitons with energy exchange were also demonstrated by combining gain bandwidth and a reverse saturable absorption effect.

High-efficiency single-photon Fock state production by transitionless quantum driving

A single-photon source is one of the key devices for optical quantum information processing. Differing from the usual stimulated Raman adiabatic passage to obtain single-photon radiation, here we propose an approach to produce an optical Fock state on demand in the usual atom–cavity system by utilizing the technique of transitionless quantum driving. The present proposal effectively suppresses the unwanted but practically unavoidable nonadiabatic transitions in the previous adiabatic schemes. Therefore, the efficiency of Fock state production by the present technique could be significantly high, even in the presence of various atomic and cavity dissipations.

The quantum/classical transition in mediated interactions

Two quantum modes interacting via local couplings to a dissipative bosonic field are investigated theoretically. The model considers two mechanical modes with distinct frequencies coupled optomechanically to the same cavity mode. The dissipative cavity field mediates the interaction between the mechanical modes but also leads to decoherence of the mechanical oscillators. Depending on the ratio between effective interaction strength and dissipation rate, which can be chosen via the pump detuning, the interaction assumes a quantum mechanical or classical character. The distinction between the two regimes is made by the ability of the mediated interaction to correlate the two mechanical modes non‐classically. For any cavity decay, there is a regime where the two mechanical modes interact in a non‐classical way, which leads us to conclude that optomechanical systems can serve as a model to experimentally study the transition of effective interactions mediated by classical or quantum‐mechanical fields.

Preparation of photonic Fock state using bichromatic adiabatic passage under dissipative environment

We propose a potentially practical scheme for generating the controllable photonic Fock state in a cavity by using the bichromatic adiabatic passage technique in the atom-cavity-laser system under dissipative environment. By numerically simulating the quantum dynamics of the whole system, we demonstrate quantitatively that the maximal probabilities of the Fock state can be achieved by elaborately adjusting the peak amplitudes of the laser's Rabi frequency and the detuning between the laser frequency and the atomic transition frequency. In addition, we have also shown that the atomic and cavity dissipations play different roles in the preparation of the Fock state inside the cavity. The experimental feasibility and challenge are justified using currently available technology. (C) 2014 Optical Society of America

Spontaneous collective coherence in driven dissipative cavity arrays

We study an array of dissipative tunnel-coupled cavities, each interacting with an incoherently pumped two-level emitter. For cavities in the lasing regime, we find correlations between the light fields of distant cavities, despite the dissipation and the incoherent nature of the pumping mechanism. These correlations decay exponentially with distance for arrays in any dimension but become increasingly long ranged with increasing photon tunneling between adjacent cavities. The interaction-dominated and the tunneling-dominated regimes show markedly different scaling of the correlation length which always remains finite due to the finite photon trapping time. We propose a series of observables to characterize the spontaneous build-up of collective coherence in the system.

Ground-state cooling of an oscillator in a hybrid atom-optomechanical system.

We investigate a hybrid quantum system combining cavity quantum electrodynamics and optomechanics, where a photon mode is coupled to a four-level tripod atom and to a mechanical mode via radiation pressure. We find that within the single-photon optomechanics and Lamb-Dicke limit, the presence of the tripod atom alters the optical properties of the cavity radiation field drastically, and gives rise to completely quantum destructive interference effects in the optical scattering. The heating rate can be dramatically suppressed via utilizing the completely destructive interference involving atom, photon and phonon, and the obtained result is analogous to that of the resolved sideband regime. The heating process is only connected to the scattering of cavity damping path, which is also far-off resonance. Meanwhile, the cooling rate assisted by the atomic transitions can be significantly enhanced, where the cooling process occurs through the cavity and atomic dissipation paths. Finally, the ground-state cooling of the movable mirror is achievable and even more robust to heating process and thermal noise.

Engineering geometric phase in semiconductor microcavities

We present rigorous investigations of the geometric phase in semiconductor microcavities. The effects of excitonic spontaneous emission, initial state setting and cavity dissipation have been discussed. It is shown that the geometric phase decays exponentially due to the presence of excitonic spontaneous emission. More importantly, the inclusion of the phase shift leads to an enhanced sensitivity for the control of the geometric phase evolution and system dynamics.

Coherent Polariton Dynamics in Coupled Highly Dissipative Cavities

Coherent light-matter interaction at the single photon and electronic qubit level promises the remarkable potential for nonclassical information processing. Against the efforts of improving the figure of merit of the cavities, here we demonstrate strong anharmonicity in the polariton dressed states via dark state resonances in a highly dissipative cavity. It is shown that vacuum Rabi oscillation occurs for a single quantum emitter inside a cavity even with bosonic decay-to-interaction rate ratio exceeding $10^{2}$, when the photon field is coupled to an auxiliary high-$Q$ cavity. Moreover, photon blockade is observable in such a highly-dissipative cavity quantum electrodynamics system. This study provides a promising platform for overcoming decoherence and advancing the coherent manipulation of polariton qubits.

Casimir Force in a One-Dimensional Cavity with Quasimode

We calculate the Casimir force between a perfect reflective wall and a semitransparent wall in the laser cavity. Using the Fox—Li quasimode theory to describe the electromagnetic field in the laser cavity, the vacuum energy and the Casimir force are calculated. We compare our results to the force in the ideal situation and find it smaller in the dissipative cavity. We also find that the Casimir force decreases with the increase of the wall-wall distance and the decay rate of the quasimodes in the laser cavity.

A concomitant and complete set of nonvolatile all-optical logic gates based on hybrid spatial solitons

We theoretically demonstrate the realization of a complete canonical set of all-optical logic gates (AND, OR, NOT), with a persistent (stored) output, by combining propagative spatial solitons in a photorefractive crystal and dissipative cavity solitons in a downstream broad-area vertical cavity surface emitting laser (VCSEL). The system uses same-color, optical-axis aligned input and output channels with fixed readout locations, while switching from one gate to another is achieved by simply varying the potential applied to the photorefractive crystal. The inputs are Gaussian beams launched in the photorefractive crystal and the output is a bistable, persistent soliton in the VCSEL with a 'robust' eye diagram and large signal-to-noise ratio (SNR). Fast switching and intrinsic parallelism suggest that high bit flow rates can be obtained.

Open Rabi model with ultrastrong coupling plus large dispersive-type nonlinearity: Nonclassical light via a tailored degeneracy

We consider a generalized version of the Rabi model that includes a nonlinear, dispersive-type atom-field interaction in addition to the usual linear dipole coupling, as well as cavity dissipation. An effective system of this sort arises, for example, in a quantum simulation of the Rabi model based upon Raman transitions in an optical cavity QED setting [A. L. Grimsmo and S. Parkins, Phys. Rev. A {\bf87}, 033814 (2013)]. For a suitable choice of the nonlinear interaction strength, near degeneracies of the states in the cavity-mode vacuum and single-photon subspaces, in combination with cavity loss, gives rise to an essentially closed cycle of excitations and photon emissions within these subspaces. Consequently, the cavity output field is strongly antibunched. We develop a quantum-trajectory-based description of the system that models its key properties very well, and use a simple dressed-state picture to explain the novel structure of the cavity fluorescence spectrum. We also present numerical results for a potential realization of the system using a rubidium atom coupled strongly to a high-finesse optical cavity mode.

Dissipative preparation of a steady three-dimensional entangled state via quantum-jump-based feedback

A robust and scalable scheme to generate a steady three-dimensional entangled state for a V-type atom and a Λ-type atom trapped in a strongly dissipative bimodal cavity is proposed by direct feedback control based on quantum-jump detection. The robustness of this scheme reflects in the insensitivity to detection inefficiencies and the strong ability against the parameter fluctuations in the feedback, driving, and coupling strengths. The influence of atomic spontaneous emission can be suppressed by using the local feedback control. The scalability is ensured that N-dimensional entangled states of two atoms can be deterministically generated.

The influences of detuning on the duperfluid-nsulator phase transition in coupled dissipative cavity arrays

In this paper, based on the effective Jaynes-Cummings-Hubbard model Hamiltonian in the presence of detuning, we use the mean-field and the perturbation theory to figure out the superfluid order parameter of the system. By which we find that detuning from resonance allows one to drive the system from the superfluid into the insulator state of the polaritons and the reverse. In addition, combining with the properties of transportation of coupled dissipative cavity arrays with detuning, we discuss the influence of detuning on the number of superfluid polaritons and the lifetime of superfluid states. It suggests that the number of the superfluid polaritons will increase to its maximum and then reduce again along the negative part of detuning, which is similar to the spectrum of the transmission.