Quantum algorithm simulates complex environments with fewer qubits

Hans Michael Christensen, Johannes Agerskov and Frederik Nathan of the NNF Quantum Computing Programme at the University of Copenhagen have developed a quantum algorithm that represents Gaussian environments as a sequential series of ancillary qubits. The researchers demonstrate their ancilla-train algorithm (ATA) can accurately reproduce the dynamics of complex quantum systems, even those with strongly coupled or non-Markovian environments, a challenge for existing simulation methods. The algorithm achieves arbitrary accuracy with a resource cost that increases at a low-degree polynomial rate relative to the desired precision. This work opens new avenues for quantum computers to efficiently simulate non-equilibrium and open quantum systems. This insight allows for a streamlined approach to simulating complex quantum systems interacting with their environments, a longstanding challenge in quantum physics. The resulting algorithm, termed the ancilla-train algorithm (ATA), efficiently simulates open quantum systems coupled to Gaussian environments regardless of configuration or coupling strength. Unlike existing…