CAREER: Taming Entanglement in Open Quantum Systems

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Entanglement is the fundamental feature of quantum mechanics that allows quantum processors to tackle specific tasks faster than their classical counterparts. The main challenge in creating and protecting entanglement is posed by decoherence: a quantum system “measured” by the environment loses its quantum correlations and is projected into classical states. Errors caused by environmental noise can be modeled as non-unitary operations acting on the qubits (basic units of quantum information) and can be overcome with quantum error correction. Therefore, understanding how entanglement propagates in quantum systems in the presence of local measurements, and which tools can be employed to govern its dynamics, are not only fundamental questions, but represent crucial steps towards building reliable and scalable quantum processors. This CAREER award supports basic research into the non-equilibrium dynamics of interacting quantum systems leading to the development of new tools for quantum information processing that will be stepping stones towards fault-tolerant quantum processors. A particular focus of this project will be the establishment of summer internship and research programs aimed at helping undergraduate students gain hands-on early research experience and at increasing the representation of women and underrepresented minorities in the quantum smart workforce.Recently, quantum simulation has emerged as a new tool that can provide insight into natural phenomena in regimes where numerical treatments fail. To date, quantum simulation experiments have focused predominantly on the dynamics of isolated systems described by unitary evolution. Conversely, this project aims to investigate non-equilibrium dynamics of interacting quantum systems subjected to well-controlled non-unitary operations, by employing the trapped-ion system’s unique features, such as pristine, individually controlled qubits. In particular, this will entail (i) the study of a symmetry-breaking dissipative phase transitions in Hamiltonian systems stemming from the competition between non-unitary (dissipative) operations and unitary evolution. (ii) The investigation of a volume law-area law entanglement phase transition, where entanglement growth changes dramatically as a function of the strength of the coupling with the environment (iii) The use of multiple qubits encodings to store and retrieve quantum information to enable a fault-tolerant trapped-ion quantum architecture. This project will lead to the development of unitary and non-unitary local operations as a powerful new tool to harness entanglement for quantum information processing. The tools developed in this project to achieve low cross-talk measurements of ancilla qubits will be stepping stones towards quantum error correction and, ultimately, fault-tolerant quantum processors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.