CAREER: Josephson Quantum Optics with Coherent Microwave Light

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

Quantum computers promise to run algorithms which are exponentially faster than their fastest known classical counterparts, as well as simulate general quantum systems. This is especially exciting in the fields of biology and chemistry where understanding complex molecules may open new avenues, for instance in drug discovery and solar cells, as well as basic research. A number of physical platforms for quantum computing exist, with two of the leading methods being optical-frequency light interacting with atomic systems (known as quantum optics) and microwave-frequency light interacting with superconducting, Josephson-junction based circuits. While each method has unique virtues, neither is yet capable of realizing large-scale quantum machines. Further, the two platforms cannot be readily combined in a single quantum circuit due to their vastly different frequencies of operation and materials requirements. This CAREER project will leverage the extreme flexibility of superconducting circuits to adapt techniques and concepts from quantum optics into a new series of hybrid devices which may be referred to as "Josephson Quantum Optics". This project will produce devices which can power a new generation of quantum machines, as well as support graduate student training in cutting-edge quantum microwave design techniques. Superconducting quantum circuits, which combine low-loss superconducting microwave elements with the nonlinear inductance of Josephson junctions, are a leading platform for realizing quantum machines, having made great progress in recent years in demonstrating the basic requirements of quantum computing. Large scale, error-free quantum computers, however, require encoding their bits of information logically across a number of physical bits so that no single error can destroy them, resulting in a huge expansion in the number of circuit elements required to build a quantum computer. An architecture in which quantum elements are linked over long distances (a specialty of the field of atomic physics and quantum optics), rather than only to their nearest neighbors, can greatly reduce the hardware overhead required to correct errors. This project will draw heavily from concepts in optical-frequency quantum optics as well as bath engineering to develop devices which generate and detect novel states of quantum light in ways that are tolerant of loss and circuit imperfections. Project research aims include the development of dc-driven highly-coherent qubit-based micromasers and an absorptive, highly-efficient Fock-state detector. The devices and concepts proposed here will advance our ability to build large, error corrected superconducting circuits. 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.