Control of superconducting qubits using a superconducting circuit at 3K.

In superconducting qubit technology, the control, monitoring, and feedback are typically accomplished using commercial off-the-shelf, and therefore large-footprint room-temperature electronics. Even as more custom electronics are used with larger scale systems, the size, power dissipation, and complexity associated with these classical components of QI systems are not scalable to the large numbers of qubits projected for a fault-tolerant quantum computer. Integration of control/readout electronics at cryogenic temperatures offers an attractive solution to these challenges and benefits from reduced latency feedback via proximity with the quantum hardware. In this talk, I will describe our use of a Josephson pulse generator (JPG) at the 3 K stage of a dilution refrigerator to digitally control a transmon qubit. I will show that we achieve comparable qubit control using both our JPG and traditional semiconductor-based control electronics. Finally, I will discuss our efforts to improve upon these results by incorporating a new JPG design that is compatible with traditional Single-Flux-Quantum logic circuits and includes a memory element for storing pulse-sequenced digital gates at cryogenic temperatures.