Josephson squelch filter for quantum nanocircuits

约瑟夫森纳米电路中的宏观纠缠

Macroscopic entanglement in Josephson nanocircuits

我们提出了一个方案，以产生和检测超导纳米电路中的电荷态之间的纠缠。我们讨论了不同的程序来区分这种纠缠的经典相关。以两个和三个耦合约瑟夫森结的最大纠缠态为例进行了讨论。

Coherent caloritronics in Josephson-based nanocircuits

We describe here the first experimental realization of a heat interferometer, thermal counterpart of the well-known superconducting quantum interference device (SQUID). These findings demonstrate, on the first place, the existence of phase-dependent heat transport in Josephson-based superconducting circuits and, on the second place, open the way to novel ways of mastering heat at the nanoscale. Combining the use of external magnetic fields for phase biasing and different Josephson junction architectures we show here that a number of heat interference patterns can be obtained. The experimental …

Fluxon-based generation of graph states in Josephson qubits

Graph states are a special kind of multiparticle entangled state with great potential for applications in quantum information technologies, especially in measurement-based quantum computers. These states cause significant reductions of the number of qubits needed for a given computation, leading to shorter execution time. Here we propose a simple scheme for generating such graph states by using special gate operations, i.e., control-phase and swap gate operations, inherent in superconducting quantum nanocircuits.

拓扑保护量子比特的超导纳米电路

Superconducting Nanocircuits for Topologically Protected Qubits

为了成功实现量子计算机，它的构建块（量子比特）应该同时是可扩展的，并充分免受环境噪声的影响。最近，已经提出了一种新的方法来保护超导量子比特。这个想法是为了防止在“硬件”层面上的错误，通过建立一个无故障（拓扑保护）的逻辑量子比特从“故障”的物理量子比特与适当的工程相互作用。已经预测，受保护的逻辑量子比特与局部噪声的解耦将随着物理量子比特的数量呈指数增长。在这里，我们报告的概念验证实验的原型设备，其中包括由纳米级约瑟夫森结制成的12个物理量子位。我们观察到，由于适当调谐的量子涨落，这个量子比特受到保护，免受磁通量变化远远超过线性秩序，与理论预测一致。这些结果证明了拓扑保护超导量子比特的可行性。

基于电流偏置信息总线的约瑟夫森量子比特量子计算

Quantum computation with Josephson-qubits by using a current-biased information bus

我们提出了一个有效的方案来操纵存储在超导纳米电路中的量子信息。约瑟夫森量子位通过它们与信息总线的单独相互作用耦合，大电流偏置的约瑟夫森结被视为具有可调频率的振荡器。总线一次仅顺序地耦合到一个量子位。没有任何直接相互作用的远距离约瑟夫森量子位可以通过与总线顺序地独立地相互作用来间接地彼此耦合，经由总线中的振动量子的激发/去激发。这是一个超导模拟的成功离子阱实验的量子计算。我们的方法不同于以前的方案，同时耦合两个量子位到总线上，而不是他们的顺序耦合在这里考虑。利用这些可调谐的选择性耦合可以实现有意义的量子逻辑门。在Bloch-Redfield形式主义内分析了所提出的量子系统的退相干性质。某些重要的实验参数的数值估计。

The Josephson heat interferometer

The Josephson effect represents perhaps the prototype of macroscopic phase coherence and is at the basis of the most widespread interferometer, i.e., the superconducting quantum interference device (SQUID). Yet, in analogy to electric interference, Maki and Griffin predicted in 1965 that thermal current flowing through a temperature-biased Josephson tunnel junction is a stationary periodic function of the quantum phase difference between the superconductors. The interplay between quasiparticles and Cooper pairs condensate is at the origin of such phase-dependent heat current, and is unique to …