The Quantum Rodeo

In “Rodeo Algorithm for Quantum Computing”, Phys. Rev. Lett 127, 040505 (2021), the authors present a stochastic quantum computing algorithm that can `prepare’ any energy state of a quantum system. The preparation process involves initializing the quantum device in some simple state and then applying quantum gates and measurements. As the name suggests, the rodeo algorithm operates by shaking off undesired quantum states until only the state with the wanted energy remains. It can be used to determine the full energy spectrum of a quantum Hamiltonian as well as prepare any specific energy state.

The rodeo algorithm is an efficient method that requires only a bare minimum of resources, and small quantum systems can already be implemented on quantum devices currently available. For quantum state preparation, the rodeo algorithm is exponentially faster than other well-known quantum algorithms such as adiabatic evolution or phase estimation. This makes it a promising candidate for future calculations of quantum many-body systems in nuclear, particle, condensed matter, and atomic and molecular physics, and quantum chemistry.

The research was carried out by members of the Lee Research Group. Kenneth Choi is a recent graduate of Ridgefield High School who will be attending MIT. Zhengrong Qian is an undergraduate, and Joey Bonitati and Jacob Watkins are Ph.D. students at MSU.

Figure: The rodeo algorithm shakes off all quantum states until only the desired energy state remains.