According to experts, "lethal applications" for quantum processors will include chemistry calculations. To achieve this, they create quantum devices that can model complex chemical processes. The evolution of a quantum wave packet near a "conical intersection," or particular arrangement of molecular energy potential, was modeled by Christopher Wang and his colleagues at Yale University using a superconducting circuit. Conical intersections are relevant to vision because similar dynamics occur when a photon strikes the ocular photoreceptor protein rhodopsin.
Conical transitions occur when the ground and excited electronic states of a molecule collide, creating a cone-shaped energy potential. As a result, the motions of the electrons and nuclei of the molecule are tightly coupled to each other. Conical intersections have been called "devilish" by theorists because this connection results in a theoretical approach that allows simulations of the electronic structure and dynamics of the system to fail.
Wang and his colleagues connected a superconducting qubit to two microwave cavities to create their conical intersection simulator. In this device, the oscillations of the vacancies reflect nuclear motion, and the states of the qubits represent the electronic states of a molecule. They programmed this system to have the same Hamiltonian as a conical intersection system using specially designed microwave pulses.
With quantum tomography measurements, they showed that the evolution of the system's quantum states exactly mimicked that of a packet of quantum waves passing through a conical intersection.
The group concedes that the simulated conical intersection is not chemically interesting because it is so simple. However, Wang claims that his experiments show that quantum devices can be specifically programmed to copy a particular Hamiltonian. According to him, this device, along with additional developments, “could form the building block of something with real processing capability”.
Source: physics.aps.org/articles/v16/s14
Günceleme: 26/01/2023 23:49
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