NSF Award
2310657
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. <br/> <br/>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.<br/><br/>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.
