Using noise to enhance quantum computation

量子计算有几种不同的模型，包括使用量子门的电路模型、基于测量的量子计算、绝热量子计算和量子行走。这些模型背后的所有理论都假设了理想的无噪声操作。然而，在所有实际的量子硬件中，与环境的相互作用是不可避免的，减少噪声和减轻不必要的影响是一个主要的工程挑战。这个项目采用了一种不同的方法，理论表明噪声有时在计算中是有用的。量子退火就是一个例子，冷却到非常低的温度有助于找到基态。噪声量可控的量子行走也保留了它们有用的量子特性。该项目将研究量子行走和量子退火，以表征噪声如何、何时以及多大程度上是有帮助的。通过理解这是如何工作来执行有用的计算，目标是将原理应用于其他量子计算模型，从而在可能的情况下利用噪声进行计算。理论和计算方法都将用于模拟量子计算机和噪声，这些模型将使用真正的量子计算机进行测试，这些计算机可以通过国家量子计算中心获得，并与斯特拉斯克莱德的实验者合作。

There are several difference models of quantum computing, including the circuit model using quantum gates, measurement based quantum computing, adiabatic quantum computing, and quantum walks. All of the theory behind these models assumes ideal noiseless operations. However, in all practical quantum hardware, interactions with the environment are unavoidable, and it is a major engineering challenge to reduce the noise, and mitigate the unwanted effects. This project takes a different approach, supported by theory showing that noise can sometimes be useful in computation. Quantum annealing is one example where cooling to very low temperatures helps to find the ground state. Quantum walks with controlled amounts of noise also retain their useful quantum properties. This project will investigate both quantum walks and quantum annealing, to characterise how and when - and how much - noise is helpful. By understanding how this works to perform useful computation, the aim is to apply the principles to other quantum computing models, and hence make use of the noise to compute, where possible. Both theoretical and computational methods will be used to model the quantum computer and noise, and the models will be tested using real quantum computers, available through the National Quantum Computing Centre, and in collaboration with experimentalists at Strathclyde.