Non-Markovianity-assisted high-fidelity Deutsch–Jozsa algorithm in diamond

Abstract

The memory effects in non-Markovian quantum dynamics can induce the revival of quantum coherence, which is believed to provide important physical resources for quantum information processing (QIP). However, no real quantum algorithms have been demonstrated with the help of such memory effects. Here, we experimentally implemented a non-Markovianity-assisted highfidelity refined Deutsch-Jozsa algorithm (RDJA) with a solid spin in diamond. The memory effects can induce pronounced nonmonotonic variations in the RDJA results, which were confirmed to follow a non-Markovian quantum process by measuring the non-Markovianity of the spin system. By applying the memory effects as physical resources with the assistance of dynamical decoupling, the probability of success of RDJA was elevated above 97% in the open quantum system. This study not only demonstrates that the non-Markovianity is an important physical resource but also presents a feasible way to employ this physical resource. It will stimulate the application of the memory effects in non-Markovian quantum dynamics to improve the performance of practical QIP.npj Quantum Information (2018) 4:3 ; doi:10.1038/s41534-017-0053-z INTRODUCTION Based on quantum phenomena, such as superposition, correlation and entanglement, quantum information processing (QIP) has provided great advantages over its classical counterpart 1-3 in efficient algorithms, 4,5 secure communication, 6,7 and highprecision metrology. [8][9][10][11][12][13][14][15][16] However, quantum superposition and correlation are fragile in an open quantum system. Notorious decoherence, [17][18][19] which is caused by interactions with noisy environments, is a major hurdle in the realization of fault-tolerant coherent operation 20,21 and scalable quantum computation. To further expand the implementation of QIP in open quantum systems, full understanding and control of environmental interactions are required. 17,[22][23][24] Many techniques have been developed to address this issue, including decoherence-free subspaces, 25 dynamical decoupling (DD) 13,26 and the geometric approach. 27 However, actively utilizing the environmental interactions would represent a significant achievement, compared with passively shielding them.Usually, the interaction of an open quantum system with a noisy environment exhibits memory-less dynamics with an irreversible loss of quantum coherence, that can be described by the Born-Markov approximation. 28 However, because of strong system-environment couplings, structured or finite reservoirs, low temperatures, or large initial system-environment correlations, the dynamics of an open quantum system may deviate substantially from the Born-Markov approximation and follow a non-Markovian process. [28][29][30][31][32] In such a process, the pronounced memory effect, which is the primary feature of a non-Markovian environment, can be used to revive the genuine quantum properties, 28-34 such as quantum coherence and correlations. Consequently, improving the performance of QIP by utilizing memo...

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