Jie Luo

Josephson Junctions in the Age of Quantum Discovery

  1. Hyunseong Kim,
  2. Gyunghyun Jang,
  3. Seungwon Jin,
  4. Dongbin Shin,
  5. Hyeon-Jin Shin,
  6. Jie Luo,
  7. Irfan Siddiqi,
  8. Yosep Kim,
  9. Hoon Hahn Yoon,
  10. and Long B. Nguyen
The unique combination of energy conservation and nonlinear behavior exhibited by Josephson junctions has driven transformative advances in modern quantum technologies based on superconducting
circuits. These superconducting devices underpin essential developments across quantum computing, quantum sensing, and quantum communication and open pathways to innovative applications in nonreciprocal electronics. These developments are enabled by recent breakthroughs in nanofabrication and characterization methodologies, substantially enhancing device performance and scalability. The resulting innovations reshape our understanding of quantum systems and enable practical applications. This perspective explores the foundational role of Josephson junctions research in propelling quantum technologies forward. We underscore the critical importance of synergistic progress in material science, device characterization, and nanofabrication to catalyze the next wave of breakthroughs and accelerate the transition from fundamental discoveries to industrial-scale quantum utilities. Drawing parallels with the transformative impact of transistor-based integrated circuits during the Information Age, we envision Josephson junction-based circuits as central to driving a similar revolution in the emerging Quantum Age.
arxiv pdf

Dynamically Reconfigurable Photon Exchange in a Superconducting Quantum Processor

  1. Brian Marinelli,
  2. Jie Luo,
  3. Hengjiang Ren,
  4. Bethany M. Niedzielski,
  5. David K. Kim,
  6. Rabindra Das,
  7. Mollie Schwartz,
  8. David I. Santiago,
  9. and Irfan Siddiqi
Realizing the advantages of quantum computation requires access to the full Hilbert space of states of many quantum bits (qubits). Thus, large-scale quantum computation faces the challenge
of efficiently generating entanglement between many qubits. In systems with a limited number of direct connections between qubits, entanglement between non-nearest neighbor qubits is generated by a series of nearest neighbor gates, which exponentially suppresses the resulting fidelity. Here we propose and demonstrate a novel, on-chip photon exchange network. This photonic network is embedded in a superconducting quantum processor (QPU) to implement an arbitrarily reconfigurable qubit connectivity graph. We show long-range qubit-qubit interactions between qubits with a maximum spatial separation of 9.2 cm along a meandered bus resonator and achieve photon exchange rates up to gqq=2π×0.9 MHz. These experimental demonstrations provide a foundation to realize highly connected, reconfigurable quantum photonic networks and opens a new path towards modular quantum computing.
arxiv pdf