论文标题
相互作用的微波光子的稳健结合状态的形成
Formation of robust bound states of interacting microwave photons
论文作者
论文摘要
相关颗粒系统出现在许多科学领域，代表了自然界中一些最棘手的难题。当相互作用与其他能量尺度相当时，这些系统的计算挑战就会产生，这使每个粒子的状态取决于所有其他粒子。缺乏针对三体问题的一般解决方案和强相关电子的可接受理论表明，当粒子数或相互作用强度增加时，我们对相关系统的理解逐渐消失。相互作用系统的标志之一是形成多粒子结合状态。在24个超导量子台的环中，我们开发了一个高保真度参数化的FSIM门，我们用来实现Spin-1/2 XXZ模型的定期量子电路，这是一种相互作用的原型模型。通过将微波光子放在相邻的量子位点中，我们研究了这些激发的传播，并观察到它们的绑定性质最多5个光子。我们设计了一种相位灵敏的方法，用于构建结合态的几个体型光谱，并通过引入合成通量来提取其伪荷利。通过引入环与其他量子位之间的相互作用，我们观察到了界面对可集成性破坏的意外弹性。这一发现违背了共同的智慧，即当它们的能量与连续频谱重叠时，非整合系统中结合的状态是不稳定的。我们的工作为相互作用的光子的结合状态提供了实验证据，并发现其稳定性超出了整合性极限。
Systems of correlated particles appear in many fields of science and represent some of the most intractable puzzles in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles. The lack of general solutions for the 3-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multi-particle bound states. In a ring of 24 superconducting qubits, we develop a high fidelity parameterizable fSim gate that we use to implement the periodic quantum circuit of the spin-1/2 XXZ model, an archetypal model of interaction. By placing microwave photons in adjacent qubit sites, we study the propagation of these excitations and observe their bound nature for up to 5 photons. We devise a phase sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the common wisdom that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit.
