My name is Junling Long. My research is based on the system of superconducting quantum circuits.
Email: Junling.Long@colorado.edu or Junling.Long@outlook.com
Ph.D., Department of Physics, University of Colorado Boulder, CO, USA, 2014/08-2020/06. Advisor: Prof. David P. Pappas.
B. S., Applied Physics, Xi'an Jiaotong University, Xi'an, China, 2010/08-2014/07. Advisor: Prof. Pei Zhang
My research is focused on studying quantum optics and quantum computing with superconducting quantum circuits.
Quantum optics with superconducting quantum circuits
Quantum optics aims for understanding and controlling the interaction between electromagnetic quanta and discrete levels in a quantum system, i.e., light-matter interaction. In the system of superconducting quantum circuits (SQC), we harness microwave photons, articial atoms, and microwave cavities to study light-matter interaction. Many qunatum optics phenomena have been revisited using SQC systems, such as Fock state generation, Autler-Townes splitting, dynamical Casimir effect, vacuum squeezing and so on. In one of our recent experiements, we designed and fabricated a supercondcuting circuit with a single artificial atom dispersively coupled to a microwave cavity. We observed electromagnetically induced transparency (EIT), very famous quantum optics phenomenon, in this circuit with microwave photons. EIT has been harnessed for implementing different building blocks of a quantum network, such as all-optical switches and transistors, quantum storage devices, and conditional phase shifters. Implementation of EIT in a SQC makes it possible to utilize EIT and related effects at the single-photon and single-atom level with highly scalable devices.
Superconducting quantum computing
The superconducting quantum circuit system has been one of the most promising candidates for building a fault-tolerant quantum computer. In recent years, the breakthroughs in both coherence time and quantum gate delity, together with the inherent scalability of superconducting qubits, are pushing superconducting quantum computers towards a size of 50 qubits. Despite this remarkable success, realizing longer coherence time and higher gate fidelity are still formidable challenges. For this research topic, I am perticularly interested in design and implementation of new type of superconducting qubits and novel two qubit gates/tunable couplers. In one of our recent experiments, we explored the ZZ interaction between two transmon qubits. We implemented a universal quantum gate set including arbitrary single qubit rotations and two qubit entangling gates. High gate fidelities of the single- and two-qubit gates are obtained using the techniques of randomized benchmarking and quantum process tomography.