Researchers at Los Alamos National Laboratory have developed quantum control techniques that can make systems appear to reverse the flow of time. The work, published in Physical Review X, uses measurements and feedback to manipulate the perceived direction of time in quantum processes.
The team introduced protocols that suppress or invert the arrow of time in quantum systems such as qubits. By combining measurements with a control Hamiltonian, the methods cancel or overcorrect disturbances to produce trajectories consistent with time moving backward.
Physicist Luis Pedro García-Pintos said the fundamental laws of physics at the microscopic level treat forward and backward time movement as equivalent. The new tools allow researchers to manipulate this symmetry for novel control of quantum systems.
The approach also enables a measurement engine that harvests energy directly from the monitoring process. This could support future quantum batteries or improved state preparation methods.
The researchers plan to test the Hamiltonian-based feedback using superconducting qubits. The work received support from the U.S. Department of Energy and the National Science Foundation.