We will add more qubits and mid-circuit measurement to increase the hardware capabilities. 'We now plan to continue to study critical phenomena in random circuits using our trapped ion quantum computer.

Chris Monroe, the principal investigator on the recent study, is now Director of this Center, and will be leading further studies works using the trapped-ion quantum computer. In their next work, the researchers will continue using the same computer, which has now been moved to the New Duke Quantum Center, to investigate other physical phenomena. Noel and her colleagues' successful realization of these two phases of the purification transition in their ion-trap quantum computer could inspire other teams to use similar systems to probe other quantum phases of matter. 'We found a way to tailor the model we studied to the system we had available, and show that with a minimal model, the critical phenomena can still be observed.' 'Critical phenomena of this nature are difficult to observe due to the need for large system sizes, mid-circuit measurement, and averaging over many random circuits taking significant computation time,' Noel said. This allowed them to observe the different phases of purification using a relatively small system. Noel and her colleagues carried out their experiments on random circuits that were optimized to work well with their ion-trap quantum computer. 'We measured the entropy of the system after the circuit evolution as we tune the rate of measurement across the transition.'Īccording to theoretical predictions, the purification phase transition probed by the team should have emerged at a critical point, resembling a fault-tolerant threshold. 'By starting in a mixed state with high entropy, or information, then evolving the circuits, the entropy at the end of the circuit indicates whether that information has been lost, or in other words the system has purified,' Noel explained. In addition, the measurements they collected included both unitary and projective measurements. To measure the purification phase transition first outlined by Gullans and Huse, the researchers had to average data collected over several random circuits. 'The main objective of our paper was to observe this critical phenomenon experimentally, using a quantum computer.' 'Our methods were based on work by Michael Gullans and David Huse, which identified a measurement-induced purification transition in random quantum circuits,' Crystal Noel, one of the researchers who carried out the study, told.

Their findings, published in a paper in Nature Physics, contribute to the experimental understanding of many-body quantum systems. Researchers at NIST/University of Maryland and Duke University have recently used a trapped-ion quantum computer to realize two measurement-induced quantum phases, namely the pure phase and mixed or coding phase during a purification phase transition.

Trapped ion quantum error correction