Generation of entangled photon strings using NV centers in diamond

Abstract

We present a scheme to generate entangled photons using the NV centers in diamond. We show how the long-lived nuclear spin in diamond can mediate entanglement between multiple photons thereby increasing the length of entangled photon string. With the proposed scheme one could generate both n-photon GHZ and cluster states. We present an experimental scheme realizing the same and estimating the rate of entanglement generation both in the presence and absence of a cavity.With controlled generation and manipulation, quantum states of light are efficient carriers of quantum information with applications in quantum computing (QC), communications and cryptography. One of the major drawbacks with optical quantum information processing (QIP) is the absence of suitable nonlinear interactions to realize universal quantum gates, for example a CNOT gate between two photonic qubits. To overcome this difficulty one may choose the implementation of desired quantum computation through a one-way quantum computer model [1] which requires the initialization of the quantum register in a globally entangled cluster state. The computation is then followed by performing only single qubit measurements. The one-way quantum computer or the measurement-based quantum computation using photonic qubits (polarization states) has already been shown to be a fault-tolerant model for QC and is tolerant to qubit losses [2]. The main hurdle in realizing optical QIP using this scheme is the generation of multi-qubit cluster state, the key initialization step of the model. While the experimental implementations succeeded to generate 6-qubit photonic cluster state optically [3], scaling this number further is not so clear. To this end there have been proposals to use solid-state emitters such as a periodically pumped quantum dot (QD) for the generation of a one-dimensional cluster states [4,5]. In this work we consider another possible solidstate system, the NV centers in diamond, to generate multi-photon entangled states.The NV center provides a hybrid spin system in which electron spins are used for fast [6], high-fidelity control [7] and readout [8,9], and nuclear spins are wellisolated from their environment yielding ultra-long coherence time [10]. Electron and nuclear spins could form a small-scale quantum register [11][12][13] allowing for e.g. necessary high-fidelity quantum error correction [11]. Furthermore, the NV electron spin can be entangled with an emitted optical photon [14,15] and further quantum entanglement [16] and quantum teleportation [17] between two remote NV centers have already been experimentally demonstrated. We have also recently demonstrated the ability of this solid-state device to store quantum information from a light field into the defect spins and a repetitive readout of the memory, essential for scalable networks. In addition there have been other proposals to create large scalable QIP in diamond using a photonic architecture [18] where cluster/topological states of the long-lived nuclear spins in various defect center...

Resonant Optical Spin Initialization and Readout of Single Silicon Vacancies in 4H - SiC

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Scalable spin–photon entanglement by time-to-polarization conversion

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Cross-entangling electronic and nuclear spins of distant nitrogen-vacancy centers in noisy environments by means of quantum microwave radiation

“…Individual control and readout of nuclear spin qubits coupled to the electronic spin has been demonstrated [17]. Besides that, the control of two nuclear spins on an individual basis, generates entanglement of two 13 C nuclear spins at the first coordination shell of the vacancy [18] and mediate the entanglement between multiple photons [19]. Numerous quantum information protocols with NV centers have been previously discussed in the literature.…”