Fault-tolerant quantum computation in realistic physical scenarios

量子计算保证了比传统方法更快的信息处理速度。具体来说，量子计算机可以实现更好的计算资源扩展，如运行时间和基本操作的数量。在某些情况下，加速是指数级的，例如使Shor的分解算法能够破解RSA加密系统。然而，量子计算机作为一种物理设备必然是不完美的，并且容易受到与环境不受控制的相互作用所产生的噪声的影响。如果不加以抵消，这些退相干效应在短时间内就会危及信息的任何量子力学处理。因此，已经开发了抵消退相干的方法，从而导致量子纠错和容错量子计算的理论可行性。执行量子纠错的能力对于构建可扩展的量子计算机至关重要。设计出来的方法现在需要应用到实验现实中去。

Quantum computation promises a much faster processing of information than is possible classically. Specifically, a drastically better scaling of computational resources such as run-time and number of elementary operations can be achieved with a quantum computer. In some cases the speed-up is exponential which e.g. enables Shor's factoring algorithm to break the RSA crypto system. However, a quantum computer as a physical device is necessarily imperfect and susceptible to noise resulting from uncontrolled interaction with its environment. If not counteracted, these decoherence effects within a short period of action jeopardize any quantum mechanical processing of information. In response, methods to counteract decoherence have been developed, leading to the theoretical viability of quantum error-correction and fault-tolerant quantum computation. The ability to perform quantum error correction is critical to building a scalable quantum computer. The devised methods now need to be brought into the realm of experimental reality.