QUANTUM INFORMATION

SUPERCONDUCTING QUBITS

Superconducting qubits are artificial atoms made with the latest technology. Quantum state manipulation techniques through the Jaynes-Cummings model have been established for decades, which has enabled the control and measurement of the cubit's state to deal with quantum states. Recently, companies such as Google and IBM are also conducting superconducting cubit research. This laboratory conducts research on Quantum Walk, Qubit state reset, and Hybrid systems.

  - Researchers: Hyeok Hwang, Jiwon Kang 

JOSEPHSON PARAMETRIC AMPLIFIER & MEASUREMENT ARCHITECTURE

As the number of qubits is rapidly scaling up, the high readout fidelity becomes more significant. To obtain high fidelity, the importance of a Josephson parametric amplifier (JPA) cannot be more emphasized since the qubit state information is generally carried by single photon-limit of microwave light. Therefore, without JPA, the signal to noise ratio(SNR) rapidly decreases as temperature increases. Thus, it is crucial to achieve the quantum limited amplification at low temperatures where not many thermal photons are allowed. In our lab, we are focusing on methods of expanding the bandwidth of JPA to measure qubit states in a wide range.

Josephson junction is the non-linear, non-dissipative element in low-temperature electric circuitry.  Josephson junction's non-linearity allows interesting devices as the diode does at the classical circuit.  The non-dissipative characteristic makes quantum application possible.  We use Josephson junction to make 3, 4 wave mixing devices such as frequency converters and amplifiers.  

  - Researchers: Taegun Joo, Gyum Lee