Array Of Coupled Cavities Research Articles

Quantum-state transmission in a cavity array via two-photon exchange

The dynamical behavior of a coupled cavity array is investigated when each cavity contains a three-level atom. For the uniform and staggered intercavity hopping, the whole system Hamiltonian can be analytically diagonalized in the subspace of single-atom excitation. The quantum state transfer along the cavities is analyzed in detail for distinct regimes of parameters, and some interesting phenomena including binary transmission, selective localization of the excitation population are revealed. We demonstrate that the uniform coupling is more suitable for the quantum state transfer. It is shown that the initial state of polariton located in the first cavity is crucial to the transmission fidelity, and the local entanglement depresses the state transfer probability. Exploiting the metastable state, the distance of the quantum state transfer can be much longer than that of Jaynes-Cummings-Hubbard model. A higher transmission probability and longer distance can be achieved by employing a class of initial encodings and final decodings.

Dissipation and excitation transmission in coupled cavity arrays: a quasi-boson approach

We have analysed the effects of dissipations on the single-photon transport in a coupled cavity array, with one of the cavities uncoupled and coupled to a two-level atom, respectively. A new approach analysing the dissipative properties of the coupled cavity arrays is first presented. We show that the coupling to a bath renormalizes the localized mode and the interaction between cavities. This permits us to redescribe the system via an effective Hamiltonian without having to mention the coordinates of the bath and then the single-photon transmission and reflection amplitudes are solved exactly. The theoretical results are in qualitatively good agreement with the experiments (Notomi et al 2008 Nature Photon. 2 741). It is shown that the dissipations of the cavity and of the atom affect distinctively the transmission of photons in the coupled cavity arrays. When the atom and the cavity are in tune, a incomplete reflect near the resonance area is mostly caused by the two-level atom dissipation, while for the large detuned cases, the reduced transmission appears to be mainly controlled by the cavity dissipation. A parameter to scale the quality of the dissipative arrays is also presented.

Artificial gauge field for photons in coupled cavity arrays

We propose and characterize solid-state photonic structures where light experiences an artificial gauge field. A nontrivial phase for photons tunneling between adjacent sites of a coupled cavity array can be obtained by inserting optically active materials in the structure or by inducing a suitable coupling of the propagation and polarization degrees of freedom. We also discuss the feasibility of observing strong gauge field effects in the optical spectra of realistic systems, including the Hofstadter butterfly spectrum.

Switching of Multiples Solitons in Arrays of Coupled Cavities

In this paper, light propagation dynamics in a coupled optical cavities array in self-defocusing configuration which has been driven by a holding beam is investigated numerically. It was shown that superposition of appropriate Gaussian control beam and plane wave holding beam can be used to write and erase of discrete cavity solitons and to switch between different orders of solitons. This method develops as an important issue of light control and all optical switches.

Switching of Multiples Solitons in Arrays of Coupled Cavities

In this paper, light propagation dynamics in a coupled optical cavities array in self-defocusing configuration which has been driven by a holding beam is investigated numerically. It was shown that superposition of appropriate Gaussian control beam and plane wave holding beam can be used to write and erase of discrete cavity solitons and to switch between different orders of solitons. This method develops as an important issue of light control and all optical switches.

Influence of electron-acoustic phonon scattering on off-resonant cavity feeding within a strongly coupled quantum-dot cavity system

We present a medium-dependent quantum optics approach to describe the influence of electron-acoustic phonon coupling on the emission spectra of a strongly coupled quantum-dot cavity system. Using a canonical Hamiltonian for light quantization and a photon Green function formalism, phonons are included to all orders through the dot polarizability function obtained within the independent Boson model. We derive simple user-friendly analytical expressions for the linear quantum light spectrum, including the influence from both exciton and cavity-emission decay channels. In the regime of semiconductor cavity-QED, we study cavity emission for various exciton-cavity detunings and demonstrate rich spectral asymmetries as well as cavity-mode suppression and enhancement effects. Our technique is nonperturbative, and non-Markovian, and can be applied to study photon emission from a wide range of semiconductor quantum dot structures, including waveguides and coupled cavity arrays. We compare our theory directly to recent and apparently puzzling experimental data for a single site-controlled quantum dot in a photonic crystal cavity and show good agreement as a function of cavity-dot detuning and as a function of temperature.

Resonant atom-field interaction in large-size coupled-cavity arrays

We consider an array of coupled cavities with staggered intercavity couplings, where each cavity mode interacts with an atom. In contrast to large-size arrays with uniform hopping rates where the atomic dynamics is known to be frozen in the strong-hopping regime, we show that resonant atom-field dynamics with significant energy exchange can occur in the case of staggered hopping rates even in the thermodynamic limit. This effect arises from the joint emergence of an energy gap in the free photonic dispersion relation and a discrete frequency at the gap's center. The latter corresponds to a bound normal mode stemming solely from the finiteness of the array length. Depending on which cavity is excited, either the atomic dynamics is frozen or a Jaynes-Cummings-like energy exchange is triggered between the bound photonic mode and its atomic analog. As these phenomena are effective with any number of cavities, they are prone to be experimentally observed even in small-size arrays.

Quantum Information Processing in An Array of Fiber Coupled Cavities

We consider a fiber coupled cavity array. Each cavity is doped with a single two-level atom. By treating the atom-cavity systems as combined polaritonic qubits, we can transform it into a polaritonic qubit-qubit array in the dispersive regime. We show that the four fiber coupled cavity open chain and ring can both generate the four qubit W state and cluster state, and can both transfer one and two qubit arbitrary states. We also discuss the dynamical behaviors of the four fiber coupled cavity array with unequal couplings.

Controlling the transport of single photons by tuning the frequency of either one or two cavities in an array of coupled cavities

We theoretically study how to control transport, bound states, and resonant states of a single photon in a one-dimensional coupled-cavity array. We find that the transport of a single photon in the cavity array can be controlled by tuning the frequency of either one or two cavities. If one of the cavities in the array has a tunable frequency, and its frequency is tuned to be larger (or smaller) than those of other cavities, then there is a photon bound state above (or below) the energy band of the coupled cavity array. However, if two cavities in the array have tunable frequencies, then there exist both bound states and resonant states. When the frequencies of the two cavities are chosen to be much larger than those of other cavities and the hopping couplings between any two nearest-neighbor cavities are weak, a single photon with a resonant wave vector can be trapped in the region between the two frequency-tunable cavities. In this case, a quantum supercavity can be formed by these two frequency-tunable cavities. We also study how to apply this photon transport control to an array of coupled superconducting transmission line resonators.

Spectral properties of coupled cavity arrays in one dimension

Spectral properties of coupled cavity arrays in one dimension are investigated by means of the variational cluster approach. Coupled cavity arrays consist of two distinct "particles," namely, photons and atomiclike excitations. Spectral functions are evaluated and discussed for both particle types. In addition, densities of states, momentum distributions and spatial correlation functions are presented. Based on this information, polariton "quasiparticles" are introduced as appropriate, wave vector and filling dependent linear combinations of photon and atomiclike particles. Spectral functions and densities of states are evaluated for the polariton quasiparticles, and the weights of their components are analyzed.

Bose-Hubbard models coupled to cavity light fields

Recent experiments on strongly coupled cavity quantum electrodynamics present new directions in "matter-light" systems. Following on from our previous work [Phys. Rev. Lett. 102, 135301 (2009)] we investigate Bose-Hubbard models coupled to a cavity light field. We discuss the emergence of photoexcitations or "polaritons" within the Mott phase, and obtain the complete variational phase diagram. Exploiting connections to the super-radiance transition in the Dicke model we discuss the nature of polariton condensation within this novel state. Incorporating the effects of carrier superfluidity, we identify a first-order transition between the superradiant Mott phase and the single component atomic superfluid. The overall predictions of mean field theory are in excellent agreement with exact diagonalization and we provide details of superfluid fractions, density fluctuations, and finite size effects. We highlight connections to recent work on coupled cavity arrays.

Simulation of a quantum phase transition of polaritons with trapped ions

We present a system for the simulation of quantum phase transitions of collective internal qubit and phononic states with a linear crystal of trapped ions. The laser-ion interaction creates an energy gap in the excitation spectrum, which induces an effective phonon-phonon repulsion and a Jaynes-Cummings-Hubbard interaction. This system shows features equivalent to phase transitions of polaritons in coupled cavity arrays. Trapped ions allow for easy tuning of the hopping frequency by adjusting the axial trapping frequency and the phonon-phonon repulsion via laser detuning and intensity. We propose an experimental protocol to access all observables of the system, which allows one to obtain signatures of the quantum phase transitions even with a small number of ions.

Scalable, high-speed one-way quantum computer in coupled-cavity arrays

We propose an efficient method to realize a scalable, high-speed quantum computer in a two-dimensional (2D) array of coupled cavities, based on coherent displacements of an arbitrary state of cavity fields in a closed phase space. Because the nontrivial geometric phase shifts fast accumulate between the qubits in nearest-neighbor cavities, a large-scale 2D cluster state can be created within a short time. We discuss the feasibility of our method for scalable solid-state quantum computation.

Long-distance entanglement and quantum teleportation in coupled-cavity arrays

We introduce quantum spin models whose ground states allow for sizable entanglement between distant spins. We discuss how spin models with global end-to-end entanglement realize quantum teleportation channels with optimal compromise between scalability and resilience to thermal decoherence and can be implemented straightforwardly in suitably engineered arrays of coupled optical cavities.

Quantum supercavity with atomic mirrors

We study single-photon transport in an of coupled microcavities where two two-level atomic systems are embedded in two separate cavities of the array. We find that a single photon can be totally reflected by a single two-level system. However, two separate two-level systems can also create, between them, single-photon quasibound states. Therefore, a single two-level system in the can act as a mirror while a different type of can be formed by using two two-level systems, acting as tunable mirrors, inside two separate cavities in the array. In analogy with superlattices in solid state physics, we call this cavity inside a coupled-cavity array a supercavity. This supercavity is the quantum analog of Fabry-Perot interferometers. Moreover, we show that the physical properties of this quantum supercavity can be adjusted by changing the frequencies of these two-level systems.

Quantum Information Processing in a Coupled Cavity Array

We consider a one-dimensional array of L identical coupled cavities, and each cavity is doped with a two-level qubit. Experimentally, it has been developed in several varieties by the newest technology. We find that the one-qubit quantum state can be perfectly transferred through the cavity array, and the entanglement between the first two qubits can also be transferred to the last two qubits. In addition, we successfully realized the entangling gate and swap gate in the coupled cavity array.

Quantum many‐body phenomena in coupled cavity arrays

AbstractThe increasing level of experimental control over atomic and optical systems gained in recent years has paved the way for the exploration of new physical regimes in quantum optics and atomic physics, characterised by the appearance of quantum many‐body phenomena, originally encountered only in condensed‐matter physics, and the possibility of experimentally accessing them in a more controlled manner. In this review article we survey recent theoretical studies concerning the use of cavity quantum electrodynamics to create quantum many‐body systems. Based on recent experimental progress in the fabrication of arrays of interacting micro‐cavities and on their coupling to atomic‐like structures in several different physical architectures, we review proposals on the realisation of paradigmatic many‐body models in such systems, such as the Bose‐Hubbard and the anisotropic Heisenberg models. Such arrays of coupled cavities offer interesting properties as simulators of quantum many‐body physics, including the full addressability of individual sites and the accessibility of inhomogeneous models.

Dynamics in a coupled-cavity array

The dynamics of a system composed of two coupled cavities, each containing a single two-level atom, is studied over a wide range of detuning and coupling values. A description of the field in terms of delocalized modes reveals that the detuning between the atoms and these modes is controlled by the coupling between the cavities; this detuning in turn governs the nature of the dynamics. If the atoms are highly detuned from both delocalized field modes, the dynamics become dispersive and an excitation may be transferred from the first atom to the second without populating the field. In the case of resonance between the atoms and one of the delocalized modes, state transfer between the atoms requires intermediate excitation of the field. Thus, the interaction between the two atoms can be controlled by adjusting the coupling between the cavities.

Ultrafast photonic crystal lasers

AbstractWe describe recent progress in photonic crystal nanocavity lasers with an emphasis on our recent results on ultrafast pulse generation. These lasers produce pulses on the picosecond scale, corresponding to only hundreds of optical cycles. We describe laser dynamics in optically pumped single cavities and in coupled cavity arrays, at low and room temperature. Such ultrafast, efficient, and compact lasers show great promise for applications in high‐speed communications, information processing, and on‐chip optical interconnects.

Polaritonic characteristics of insulator and superfluid states in a coupled-cavity array

Recent studies of quantum phase transitions in coupled atom-cavity arrays have focused on the similarities between such systems and the Bose-Hubbard model. However, the bipartite nature of the atom-cavity systems that make up the array introduces some differences. In order to examine the unique features of the coupled-cavity system, the behavior of a simple two-site model is studied over a wide range of parameters. Four regions are identified, in which the ground state of the system may be classified as a polaritonic insulator, a photonic superfluid, an atomic insulator, or a polaritonic superfluid.