Controlled Photon Switch Assisted by Coupled Quantum Dots

Abstract

Quantum switch is a primitive element in quantum network communication. In contrast to previous switch schemes on one degree of freedom (DOF) of quantum systems, we consider controlled switches of photon system with two DOFs. These controlled photon switches are constructed by exploring the optical selection rules derived from the quantum-dot spins in one-sided optical microcavities. Several double controlled-NOT gate on different joint systems are greatly simplified with an auxiliary DOF of the controlling photon. The photon switches show that two DOFs of photons can be independently transmitted in quantum networks. This result reduces the quantum resources for quantum network communication.

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

“…Thus our four Toffoli gates are deterministic and faithful. However, the side leakage from the cavity is unavoidable in the experiment [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]. In this case, the reflectance coefficients r 0 and r h are shown in figure 7.…”

“…Generally, implementation of a Toffoli gate requires six CNOT gates and 10 single-qubit operations [19]. In recent years, Ralph et al [20], Lanyon et al [21] and Luo et al [22] have demonstrated a general technique that harnesses multi-level information photonic carriers to realize a three-qubit Toffoli gate with reduced CNOT gates.…”

“…Hence, their hybrid systems are used in our schemes to assist each other. Motivated by the schemes in [20][21][22], we present compact circuits of a Toffoli gate on remote three-qubit systems using an auxiliary extra-level logic state. Recent results have shown that quantumdot spins in one-sided optical microcavities or double-sided optical microcavities [28][29][30][31][32] may provide a giant optical circular birefringence.…”

“…Recent results have shown that quantumdot spins in one-sided optical microcavities or double-sided optical microcavities [28][29][30][31][32] may provide a giant optical circular birefringence. With its superiorities, the cavity-quantum electrodynamics (QED) system has been widely used in quantum information processing [33][34][35][36][37][38][39][40][41][42], entanglement concentration [43][44][45][46][47][48][49] and scalable quantum computing [50][51][52][53][54][55][56]. 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).…”

Generations of N-atom GHZ state and $$2^n$$ 2 n -atom W state assisted by quantum dots in optical microcavities

“…This architecture may be a good candidate to distribute quantum information over a long distance. In experiment, the QED has been applied to generate photonic entanglements [38][39][40], transmit quantum states between light and a single trapped atom [41,42], or provide the photon routers [43][44][45]. The strong coherent interactions between atoms and photons have inspired lots of researches in quantum information processing [46][47][48].…”