Implementation of Dynamically Corrected Gates on a Single Electron Spin in Diamond

Abstract

Precise control of an open quantum system is critical to quantum information processing, but is challenging due to inevitable interactions between the quantum system and the environment. We demonstrated experimentally at room temperature a type of dynamically corrected gates on the nitrogen-vacancy centers in diamond. The infidelity of quantum gates caused by environment nuclear spin bath is reduced from being the second-order to the sixth-order of the noise to control field ratio, which offers greater efficiency in reducing the infidelity by reducing the noise level. The decay time of the coherent oscillation driven by dynamically corrected gates is shown to be two orders of magnitude longer than the dephasing time, and is essentially limited by spin-lattice relaxation. The infidelity of DCG, which is actually constrained by the decay time, reaches 4 × 10 −3 at room temperature and is further reducible by 2-3 orders of magnitudes via lowering temperature. The greatly reduced noise dependence of infidelity and the uttermost extension of the coherent time mark an important step towards fault-tolerant quantum computation in realistic systems. Quantum information processing can provide a dramatic speed-up over classical computer for certain problems [1]. One of the most urgent demands in quantum computation is to realize noise-resistant universal quantum gates for qubits. Strategies including quantum error correction [2-4], decoherence-free subspace [5,6], and dynamical decoupling (DD) [7] have been developed to accomplish this task. Compared with the other two strategies, the resource requirements for the DD are modest [8], and no extra qubits is required. It uses stroboscopic qubit flips to average out the coupling to the environment.There are experiments to demonstrate DD as a successful technique in preventing the quantum states from being destroyed in open systems [9][10][11]. However, implementing DD in quantum gates is still of challenge, because in general the gate operation may not commute with the DD control. Recently, there are theoretical studies to address this problem via dynamically corrected gates (DCGs) [12][13][14][15], but experimental implementation is still elusive.Herein, we experimentally demonstrated a type of DCG, namely SUPCODE [14], in a single electron spin in diamond at room temperature. We experimentally verified that the SUPCODE reduces the error stemming from magnetic field fluctuation to the sixth-order of the fluctuation field to control field ratio, and largely diminishes the decoherence effect. The performance of quantum gate has been protected far beyond the quantum system's dephasing time T * 2 and is approximately limited by the spin-lattice relaxation time T 1 . Our successful demonstration of decoherece-protected universal quantum control is important for future quantum computations based on solid-state devices.The Hamiltonian describing a general single-qubit unitary operation on an electron-spin qubit in the rotating frame can be described as H C = ω 1 n · S, where 2 ] cos...

Universal quantum gates between nitrogen-vacancy centers in a levitated nanodiamond

“…Pulse sequences of 5-piece SUPCODE sequences [52]. The time duration τ0 = (2 + θ/2π)t0 for a θ rotation pulse.…”

Detection of radio-frequency field with a single spin in diamond

“…1b, the NV center consists of a substitutional nitrogen atom and an adjacent vacancy. The NV center systems are convenient to initialize and read out [13][14][15], have long coherence times [16] and can be manipulated by alternating field [17][18][19][20] with high precision at room temperature. In addition, the NV sensor can reach a sub-nanometer resolution.…”

Floquet engineering to entanglement protection of distant nitrogen vacancy centers

“…Among the solid-state spins, the diamond nitrogen vacancy center (NVC) are particularly attractive, owing to extremely long electronic and nuclear spin lifetimes, well qubit readout, fast initialization as well as robust optical interface [1][2][3][4][5][6] . Until now, several hallmark demonstrations on the entanglement between NVCs have been achieved experimentally using the method of magnetic dipolar coupling [7], strong nonclassical correlations between Raman-scattered photons [8], entanglement swapping [9,10], and projective measurements [11,12], respectively.…”