Scalable measures of magic resource for quantum computers

Abstract

Magic characterizes the degree of non-stabilizerness of quantum states. It is a crucial resource for quantum computing and a necessary condition for quantum advantage. However, quantifying magic beyond a few qubits has been a major challenge. Here, we introduce Bell magic to efficiently measure magic for any number of qubits. Our method can be easily implemented in experiments together with a cost-free error mitigation scheme. We experimentally demonstrate the transition of classically simulable stabilizer states into intractable quantum states on the IonQ quantum computer. For applications, Bell magic distinguishes stabilizer and magical states with a low measurement cost. Further, variational quantum algorithms can maximize the magic of quantum states via the shift-rule. Our results pave the way to benchmark the non-classical power of quantum computers, quantum simulators and quantum many-body systems.

Multipartite entanglement measures via Bell basis measurements

“…More recently, Bell basis measurements have been implemented experimentally to estimate bipartite concurrences [30,31], non-stabilizerness (i.e. magic) [32], entanglement dynamics in many-body quantum systems [33][34][35][36], and even to demonstrate quantum advantage in learning from experiments [37]. These recent experiments corroborate the claim that our methods are feasible on today's hardware.…”

Faster Born probability estimation via gate merging and frame optimisation

“…Such results hint towards the ingredients that may be sufficient to achieve quantum advantage. It is also possible to approach the boundary from the other side, namely by finding efficient methods to classically simulate families of quantum circuits [18][19][20][21][22][23][24], thereby providing insights on what ingredients are necessary for quantum advantage.…”