Analog Quantum Simulation of the Dynamics of Open Quantum Systems with Quantum Dots and Microelectronic Circuits

物理科学的一个中心目标是发展根据量子力学规则对物质动力学进行建模的能力。然而，这样做的计算成本随着系统大小呈指数级增加，将我们的预测能力限制在具有几个自由度的系统。在这种背景下，量子计算机有可能彻底改变我们建模和理解物质的能力，因为它们执行某些计算的速度比经典计算机快得多。然而，尽管正在进行研究，但创造一台通用的容错量子计算机仍然超出了当今技术的能力范围，因此不是短期内的事情。量子信息处理器的一个近期应用是模拟量子模拟，在这种模拟量子模拟中，感兴趣的物理问题被映射到专门为此目的而设计的高度可控的量子设置上，并允许大自然进行计算。模拟仿真的概念并不新鲜。例如，风洞通常被用来模拟水动力问题，而这些问题对于传统计算来说太具有挑战性了。就像在常规模拟中一样，这些模拟模拟器允许连续调整模拟参数，从而能够以直接实验无法企及的方式询问物质的行为。这个项目的目标是开发一种模拟量子模拟器的通用蓝图，该模拟器可以用来理解分子在热环境中的激发态动力学。例如，这是开发更好的有机太阳能电池或了解光合作用和视觉等重要过程所必需的。该项目代表了分子模拟方法生态系统中的一种新策略，并有可能在化学、物理和量子信息科学的应用中具有普遍用途。具体地说，这个项目的目标是开发一种新的模拟量子模拟器的理论，用于开放量子系统的动力学，利用半导体量子点和量子电子电路。为了对系统建模，PI将使用门定义的半导体量子点，因为它们使设计高度可配置和相干的量子系统成为可能。为了模拟环境，PI将引入由量子电子电路阵列组成的量子浴合成器的概念。这种方法的基础是冷却RLC电路，直到它们的行为像耗散量子力学振荡器一样。通过合理地控制电路的电阻R、电感L和电容C，可以定制每个振荡器的频率、量子涨落和驰豫。通过考虑一系列具有不同频率的化学物质，物理系统就像一个量子热环境，可以进行调整，以模拟甚至复杂的化学环境的动力学和响应。在这个项目中，PI将在物理问题和量子硬件之间建立有用的映射，以最大限度地提高模拟保真度，最大限度地减少实验要求。模拟器的操作和实用性将通过模拟器的计算机仿真进行测试。来自理论和模拟的见解将被用来建立一个有用的映射，用于基于耦合到量子浴合成器的量子点阵列来模拟分子阵列中激子的耗散动力学，例如光合作用复合体或哈伯德链。该模拟器最终可用于了解现实量子设备的操作，设计增强分子功能的量子环境，根据量子技术的需要分离具有增强相干属性的分子量子比特，了解光合作用的基本步骤，并在量子环境下测试量子控制策略。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

A central goal in the physical sciences is to develop the capabilities to model the dynamics of matter according to the rules of quantum mechanics. However, the computational cost of doing so increases exponentially with system size, limiting our predictive capabilities to systems with a few degrees of freedom. In this context, quantum computers offer the potential to revolutionize our ability to model and understand matter because they can perform some calculations much faster than classical computers. However, despite ongoing research, creating a universal and fault-tolerant quantum computer remains beyond the reach of present-day technology and is thus not near-term. One near-term application of quantum information processors is analog quantum simulation, where the physical problem of interest is mapped onto a highly controllable quantum setup specifically designed for this purpose, and nature is allowed to do the calculations. The concept of analog simulation is not new. For instance, wind tunnels are routinely used to simulate hydrodynamic problems that are simply too challenging for conventional computation. Just as in regular simulations, these analog simulators allow continuously tuning simulation parameters, thus enabling interrogating the behavior of matter in ways that are beyond the reach of direct experimentation. The objective of this project is to develop a general blueprint for an analog quantum simulator that can be used to understand the excited state dynamics of molecules immersed in thermal environments. This is needed, for example, to develop better organic solar cells or understand vital processes such as photosynthesis and vision. The project represents a novel strategy in the ecosystem of molecular simulation methods and has the potential to be of general utility in applications in chemistry, physics and quantum information science. Specifically, the goal of this project is to develop the theory of a new analog quantum simulator for the dynamics of open quantum systems, harnessing semiconductor quantum dots and quantum electronic circuits. To model the system the PI will use gate-defined semiconductor quantum dots as they enable the design of highly configurable and coherent quantum systems. To model the environment the PI will introduce the concept of a quantum bath synthesizer that is composed of arrays of quantum electronic circuits. The approach is based on cooling RLC circuits until they behave like dissipative quantum mechanical oscillators. By judiciously controlling the resistance R, inductance L, and capacitance C of the circuits, the frequency, quantum fluctuations and relaxation of each oscillator can be tailored. By considering an array of them with different frequencies, the physical system acts as a quantum thermal environment that can be tuned to mimic the dynamics and response of even complex chemical environments. In this project, the PI will establish useful mappings between the physical problem and the quantum hardware that maximize simulation fidelity and minimize experimental requirements. The operation and utility of the simulator will be tested through computer emulations of the simulator. The insights from theory and simulation will be used to establish a useful mapping for the simulation of the dissipative dynamics of excitons in molecular arrays such as photosynthetic complexes or Hubbard chains, based on arrays of quantum dots coupled to the quantum bath synthesizer. The simulator could eventually be used to understand the operation of realistic quantum devices, to engineer quantum environments that enhance molecular function, to isolate molecular qubits with enhanced coherence properties as needed for quantum technologies, to understand elementary steps in photosynthesis, and to test quantum control strategies in the presence of quantum environments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.