High-fidelity quantum memory using nitrogen-vacancy center ensemble for hybrid quantum computation

Abstract

We study a hybrid quantum computing system using a nitrogen-vacancy center ensemble (NVE) as quantum memory, a current-biased Josephson junction (CBJJ) superconducting qubit fabricated in a transmission line resonator (TLR) as the quantum computing processor, and the microwave photons in TLR as the quantum data bus. The storage process is seriously treated by considering all kinds of decoherence mechanisms. Such a hybrid quantum device can also be used to create multiqubit W states of NVEs through a common CBJJ. The experimental feasibility is achieved using currently available technology.

Quantum-information processing on nitrogen-vacancy ensembles with the local resonance assisted by circuit QED

“…Recently, the hybrid quantum system made up of NVEs and superconducting circuits has been studied for quantum computation [50][51][52]. In the system, the coupling strength between an NVE and a TLR can be enhanced to about 10 ∼ 65 MHz [47,49], and the NVE can act as either a qubit or a good memory because the coherence time of an NV-center is much longer than that of an SPQ [46].…”

“…The two TLRs are interconnected by an SPQ. The TLR with inductance L and capacitance C can be modeled as a simple harmonic oscillator [24,26] consisting of a narrow center conductor and two nearby lateral ground planes [51,52]. The Hamiltonians of TLR a and TLR b can be formed as…”

“…As a result of long coherence time of the NV-center spin [46] and the * Corresponding author: aiqing@bnu.edu.cn strong coupling between nitrogen-vacancy-center ensemble (NVE) and superconducting resonator [47][48][49], the hybrid system composed of diamond NVE and superconducting circuit plays a good platform for quantum information processing. Recently, a lot of theoretical and experimental works have been done in the quantum information processing based on the hybrid system [47,[49][50][51][52]. For example, in 2010, Kubo and coworkers [47] realized the strong coupling of a spin ensemble, which is composed of NV-centers in a diamond crystal, to a superconducting resonator.…”

“…In 2011, Kubo et al [50] reported the experimental realization of a hybrid quantum circuit combining a superconducting transmon qubit and an NVE. Yang et al [51] studied the high-fidelity quantum memory in a hybrid quantum computing system composed of an NVE and a current-biased Josephson-junction superconducting phase qubit in a transmission line resonator (TLR) (as the quantum data bus). They also [52] presented a potentially practical proposal for creating entanglement of two distant NVEs coupled to separated TLRs interconnected by a current-biased Josephson-junction superconducting phase qubit.…”

Hybrid quantum circuit consisting of a superconducting flux qubit coupled to a spin ensemble and a transmission-line resonator

“…In one approach, both of the atomic system and the SC qubit couple to a common SC resonator, which plays the role of a data bus. [13][14][15][16][17][18][19][20] Due to the weak coupling between a single atom (or spin) and the SC resonator, an ensemble with a large number N of atoms (or spins) is employed for enhancing the coupling strength by a factor of √ N . Recently, this approach has been experimentally demonstrated (see Ref.…”