Distributed Quantum Computation via Optical Fibers

Abstract

We investigate the possibility of realising effective quantum gates between two atoms in distant cavities coupled by an optical fibre. We show that highly reliable swap and entangling gates are achievable. We exactly study the stability of these gates in presence of imperfections in coupling strengths and interaction times and prove them to be robust. Moreover, we analyse the effect of spontaneous emission and losses and show that such gates are very promising in view of the high level of coherent control currently achievable in optical cavities.

Dynamics of interacting Dicke model in a coupled-cavity array

“…There are various techniques to minimize population of the cavity modes or fiber while performing a quantum state transfer [13]. Alternatively a sufficiently strong cavity-fiber coupling effectively eliminates the degrees of freedom of the fiber from the dynamics of the system [14]. Similarly, the use of highly detuned qubitscavity mode reduces the chance of cavity-mode population.…”

“…Systems of coupled cavities have received much attention recently [15][16][17][18][19][20][21][22] due to the easy handling of the individual sites (using an optical laser) and the presence of relatively long-lived atomic states suitable for encoding a quantum information. Furthermore, such systems provide a number of degrees of freedom to control dynamics of the system in a better way where photons are allowed to hop between neighboring cavities.…”

“…Similarly, photon-blockade effects have ben studied, thus paving the way to the observation of the predicted polaritonic Mott insulator phase [17,19]. In the strong hopping regime, various aspects of the transfer of quantum excitations between qubits without populating cavity modes have been analyzed [15,16,18,20,21].…”

Arbitrary control of coherent dynamics for distant qubits in a quantum network

“…Recently, schemes have been proposed [8][9][10] to realize quantum communication, deterministic entanglement, and phase gates between two atomic qubits trapped in separate optical cavities, which are coupled by an optical fiber via coherent dynamics. These previous works [8][9][10] concentrate on the simplest case: the system is only composed of two nodes.…”

“…These previous works [8][9][10] concentrate on the simplest case: the system is only composed of two nodes. In order to implement a distributed quantum computational network with several nodes, it is necessary to be able to control the coupling of different nodes, exploit suitable coupling dynamics to perform desired logic operations between any pair of nodes, and engineer entanglement among these nodes.…”