Proposed entanglement beam splitter using a quantum-dot spin in a double-sided optical microcavity

Abstract

We propose an entanglement beam splitter (EBS) using a quantum-dot spin in a double-sided optical microcavity. In contrast to the conventional optical beam splitter, the EBS can directly split a photon-spin product state into two constituent entangled states via transmission and reflection with high fidelity and high efficiency (up to 100 percent). This device is based on giant optical circular birefringence induced by a single spin as a result of cavity quantum electrodynamics and the spin selection rule of trion transition (Pauli blocking). The EBS is robust and it is immune to the fine structure splitting in a realistic quantum dot. This quantum device can be used for deterministically creating photon-spin, photon-photon and spin-spin entanglement as well as a single-shot quantum non-demolition measurement of a single spin. Therefore, the EBS can find wide applications in quantum information science and technology.

Extended linear regime of cavity-QED enhanced optical circular birefringence induced by a charged quantum dot

“…Quantum gates are the key components for quantum information processing in an analog to the classical gates for classical information processing. To design deterministic quantum gates, three types of interactions can be exploited, i.e., photon-photon interactions [10][11][12], spin-spin interactions [13][14][15][16][17][18], and photon-spin interactions [19][20][21][22][23][24]. Although photons do not interact directly with each other intrinsically, photon-photon indirect interactions mediated by cavity QED have been demonstrated but are by definition nonlinear phenomena.…”

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

“…Meanwhile, the finite linewidth of the input light pulse will inevitably make the resonant condition diffusion. The side leakage of the cavity κ s and the limited coupling strength g will lead to the imperfect birefringent propagation of the input photons [22,28] as well. For instance, when the electron spin is in the spin-up state | ↑ , the incident photon |R ↑ or |L ↓ totally reflected in the ideal case has a probability t to be transmitted through the cavity, and |L ↑ or |R ↓ supposed to be totally transmitted has a probability r 0 to be reflected.…”

“…Let us consider a singly charged QD (e.g., for a selfassembled InAs/GaAs quantum dot) embedded inside a resonant double-sided micropillar cavity [22]. Both the top and bottom mirrors of the cavity are partially reflective, shown in Fig.…”

“…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].…”