![]() Physicists and quantum chemists consider coherent quantum regulation of small molecules to be one of the "holy grails" of chemical science. They envision efforts in this direction to encompass topics such as photochemistry and laser excitation. ![]() They selected two key areas of interest in chemistry, and estimated the requisite quantum resources to simulate the dynamics of strong external fields, followed by simulations of particle scattering dynamics.ĭuring the first experiment, the team applied an external field suddenly with resulting dipole oscillation and ionization of a single bound electron. The team used the experimental setup to explore several informative scenarios for 2D and 3D simulations of one- and two-electron systems. The costs of mimicry limited the quantum computer-emulations to modest-sized versions containing 36 perfect qubits. While they did not rehash pre-existing classical-grid techniques to perform grid-based simulations, they conducted emulations of real, noise-free quantum machines for chemically relevant quantum dynamics instead. The researchers therefore took a different approach by deploying classical computing resources to emulate small, but noise-free quantum computers to thereby simulate quantum molecular dynamics within them-to directly examine the costs and performance measures. Most quantum computers are noise-burdened and costly. The team encoded features such as particle symmetry to offer optimal resource scaling for complex and interesting molecules during the study. These early versions of quantum computers had a limited number of error-corrected qubits. In this work, Chan and colleagues studied the underlying characteristics of accelerating chemical dynamics simulations on early versions of quantum computers based on a real-space grid approach. While conventional computers are useful to explore quantum molecular dynamics to predict reaction outcomes and experimental observables, the hardware costs and time duration can scale exponentially with the number of simulated particles. Quantum chemists envision quantum computers to be transformative tools for chemistry prediction and exploration. Quantum computing via a real-space grid approach The grid-based method performed exceptionally to make way for a less error-prone quantum computing era. In this work, quantum chemists explored a range of tasks from ground state preparation and energy estimation to scattering and ionization dynamics of electrons, to assess a variety of methods in the split-operative simulation in order to emulate the quantum chemistry of a few molecules of interest. In a new report now featured on the cover page of and published in Science Advances, Hans Hon Sang Chan and a research team in materials, chemistry and quantum photonics at the University of Oxford generated exactly emulated quantum computers with up to 36 qubits to explore resource-frugal algorithms and model two- and three-dimensional atoms with single and paired particles.Ĭhemistry modeling is a natural attribute for quantum computers, although existing methods are impractical to develop near-perfect qubits. The left inset plot zooms in on the energy error at high temporal resolutions for the ground state. (C) The difference between the final and initial energy expectation value, measured by direct sampling of the state, of the ground state (left), and the first excited state (right), propagated at different spatial and time resolutions. These two states, represented at different spatial resolutions, are all time-propagated using the first-order SO for 1.5 atomic time units. We also initialize the ψ1,1 excited state in a simulation box with sides of length 40 a.u., with budgets of 7 ≤ nr ≤ 10 qubits per subregister and corresponding resolutions of 0.313 ≥ δr ≥ 0.039 a.u. Each subregister has a budget of 8 ≤ nr ≤ 12 qubits to store the wave function, corresponding to spatial resolutions of 0.039 ≥ δr ≥ 0.002 a.u. In this series of experiments, we initialized the ground state ψ0,0 centered in a simulation box with L = 10 a.u., such that the origin of the Coulomb singularity lies halfway between two central grid points. Bottom captures the deviation of the simulation fidelity at the end of the propagation. (B) Top represents difference between the energy from phase estimation and the analytic energy of 2D hydrogen. Note that the plots here do not reflect the choice of simulation box size and are not to scale. ![]() (A) Real projections of the ground ψ0,0 state (left) and a first excited ψ1,1 state (right) of 2D hydrogen. SO-QFT simulation of 2D hydrogenic electron.
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