Quantum error correction of spin quantum memories in diamond under a zero magnetic field

Abstract

Fault-tolerant quantum memory plays a key role in interfacing quantum computers with quantum networks to construct quantum computer networks. Manipulation of spin quantum memory generally requires a magnetic field, which hinders the integration with superconducting qubits. Completely zero-field operation is desirable for scaling up a quantum computer based on superconducting qubits. Here we demonstrate quantum error correction to protect the nuclear spin of the nitrogen as a quantum memory in a diamond nitrogen-vacancy center with two nuclear spins of the surrounding carbon isotopes under a zero magnetic field. The quantum error correction makes quantum memory resilient against operational or environmental errors without the need for magnetic fields and opens a way toward distributed quantum computation and a quantum internet with memory-based quantum interfaces or quantum repeaters.

Deterministic Bell state measurement with a single quantum memory

“…The development of large-scale distributed quantum computers requires quantum networks [1][2][3] based on remote entanglement to connect the computers [4][5][6][7][8][9][10] and thus requires quantum repeaters [11][12][13][14] or quantum interfaces 15 that can perform a deterministic and complete Bell state measurement (BSM) [16][17][18][19] not only to extend the distance of photon transmission and to route photons over the networks but also to interface the quantum state between photons and qubits in quantum computers 15,[20][21][22] . A complete BSM allows us to project any two-qubit states into one of the four Bell states deterministically, which typically requires quantum nondemolition measurement known as single-shot measurement [23][24][25][26][27][28] . Due to quantum manipulability with communicating photons [29][30][31][32][33][34] , as well as the coherence time of solid-state spins 33,[35][36][37][38][39][40][41] , which is over a minute for a nuclear spin…”

“…1d. The Bell states are composed of inherently degenerate qubits, which we call geometric spin qubits 19,28,32,34,[49][50][51][52][53][54][55][56] , according to the computational basis states | ± 1⟩ e for the electron and | ± 1⟩ N for the nitrogen (dashed area in Fig. 1d), and are operated by the universal holonomic quantum gate with polarized MW and RF pulses via the ancilla states |0⟩ e and |0⟩ N 55 .…”

Implantation site design for large area diamond quantum device fabrication

“…Quantum centers in diamond have been widely investigated for both quantum optics 1 and quantum computing applications 2 – 4 , due to their versatility 5 , 6 and room temperature stability 7 . Among many different quantum centers in diamond, one of the most well-known is nitrogen vacancy (NV) center.…”

Precession-induced nonclassicality of the free induction decay of NV centers by a dynamical polarized nuclear spin bath

“…To acquire insights into the system-environment interactions giving rise to the classicality-nonclassicality transition, meanwhile underpinning the practical viability of this approach, we will discuss the CHER of the free-induction-decay (FID) process of the electron spin associated with a single negatively charged nitrogen-vacancy (NV − ) center in diamond. Due to its unique properties, particularly its long coherence time even at room temperature [38][39][40][41][42], NV − centers are a promising candidate for applications in various branches of quantum technologies, ranging from quantum information processing [42][43][44][45][46][47], highly-sensitive nanoscale magnetometry [48,49] and electrometry [50,51], bio-sensing in living cells [52,53], emerging quantum materials [54][55][56], to test bed of fundamental quantum physics [57]. The primary source of decoherence of the electron spin comes from the hyperfine interaction to the nuclear spin bath of carbon isotopes 13 C randomly distributed in the diamond lattice.…”