arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1902.04709quant-ph
收藏

量子退火中热力学效应的实验和理论研究

Experimental and Theoretical Study of Thermodynamic Effects in a Quantum Annealer

Tadashi Kadowaki, Masayuki Ohzeki

摘要:

量子器件受到固有噪声和环境噪声的影响。噪声效应的深入表征对于利用噪声量子计算是必不可少的。为此,我们通过实验和数值模拟研究了量子退火器的能量耗散行为。我们的研究采用了最近提出的纯量子动力学和纯热力学之间的插值技术。实验在具有退火暂停功能的量子退火机上进行,该退火暂停功能通过暂停作为量子涨落源的横向场来将热弛豫期插入到退火时间表中。在研究了表征系统量子热力学的特殊哈密顿量之后,我们观察到了依赖于退火暂停参数的热力学签名的增强。在开放量子模拟中观察到的态矢量随时间的发展,为研究能隙分析之外的现象提供了丰富的信息。我们确定了一种特殊的本征态桥,即在希尔伯特空间中相距很远的基态,并确定了从一个基态到另一个基态的转移几率。这一发现可以通过减小在量子退火器中寻找经典基态时的采样偏差来改善采样均匀性。我们的研究不仅描述了特定哈密顿量的开量子现象,而且证明了该方法在研究噪声量子器件中的有用性。

英文摘要:

Quantum devices are affected by intrinsic and environmental noises. An in-depth characterization of noise effects is essential for exploiting noisy quantum computing. To this end, we studied the energy dissipative behavior of a quantum annealer via experiments and numerical simulations. Our investigation adopts a recently proposed technique that interpolates between pure quantum dynamics and pure thermodynamics. Experiments were conducted on a quantum annealer with an anneal pause function, which inserts a thermal relaxation period into the annealing schedule by pausing the transverse field, which is a source of quantum fluctuation. After investigating the special Hamiltonian that characterizes the quantum thermodynamics of the system, we then observed enhancement of thermodynamic signature depending on the anneal pause parameter. The time development of the state vector, observed in the open quantum simulation, provides rich information for investigating phenomena beyond energy-gap analysis. We identified a special eigenstate bridges ground states far-separated in Hilbert space and the transfer probabilities from one ground state to another. This finding can improve the sampling uniformity by reducing the sampling bias in finding the classical ground states in the quantum annealer. Our study does not only characterize the open quantum phenomenon of the specific Hamiltonian but also demonstrates the usefulness of the method in investigating noisy quantum devices.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑