Optically controlled phase gate and teleportation of a controlled-not gate for spin qubits in a quantum-dot–microcavity coupled system

Abstract

Using linear optical manipulation, single photons, entangled photon pairs, photon measurement, and classical communication, we propose a scheme for a two-spin-qubit phase gate and the teleportation of a controlled-NOT gate between two electron spins from acting on local qubits to acting on remote qubits using quantum dots in optical microcavities. The scheme is based on spin selective photon reflection from the cavity and is achieved in a deterministic way by the sequential detection of photons and the single-qubit rotations of a single electron spin in a self-assembled GaAs-InAs quantum dot. The feasibility of the scheme is assessed showing that high average fidelities of the gates are achievable in the weak-coupling regime when the side leakage and cavity loss are low. The scheme opens promising possibilities for long-distance quantum communication, distributed quantum computation, and construction of remote quantum-information-processing networks.

Universal remote quantum computation assisted by the cavity input–output process

“…is used as a ququart system [20][21][22] to reduce the CNOT gate. With this assistance, the entanglement resources are greatly reduced in contrast to previous remote CNOT gates [57][58][59][60]. Of course, with their results [55], similar remote Toffoli gate may be performed assisted by bad cavities.…”

“…Based on new transformation rules, the average fidelities F of the four Toffoli gates may be calculated as illustrated in figure 8 by making use of the cooperativity C = g 2 /(κγ ) [57][58][59][60][61][62][63][64][65][66][67][68][69],…”

“…For simplicity, by exploring the giant optical-controlled gate induced by quantum-dot spins in one-sided optical microcavities, a Toffoli gate may be deterministically implemented on remote threespin systems using only one photonic Einstein-Podolsky-Rosen (EPR) pair or EPR pair of spin systems and local quantum operations and classical communication (LOCC). In comparison with a previous remote CNOT gate with one EPR pair [57][58][59][60], our schemes have greatly reduced the entanglement cost for distribution quantum computation. These schemes may be also adapted to implement Toffoli gates on a remote hybrid three-qubit system.…”

Heralded quantum repeater for a quantum communication network based on quantum dots embedded in optical microcavities

“…In other words, the circularly polarized photon directed into the spin-cavity system can either be coupled with the electron spin and feels a hot cavity when the dipole selection rule is fulfilled, or be decoupled and feels a cold cavity in the other case. The significant difference in the reflection and the transmission coefficients manifested between these two cases is spin dependent, and it can be exploited to perform the quantum information processing [22][23][24][25][26][27][28][29][30].…”

“…Single semiconductor QD coupling to a microcavity has attracted much attention [22][23][24][25][26][27][28][29][30][31][32]. The giant circular birefringence originated from the spin selective dipole coupling for such spin-cavity systems is utilized in photon-photon or spin-photon entanglement generation [22], hyper-parallel quantum computing [23], universal quantum gates [24][25][26], hyperentanglement purification and concentration [27], and complete Bell-state analyzers [28]. In 2006, Waks and Vuckovic put forward a quantum repeater scheme with the QD-cavity system [29].…”