Quantum bits (aka qubits) of quantum processors are cooled to mK temperatures to avoid thermal disturbance of their states, While qubits operate at such low temperatures, their control and readout is performed with racks of room-temperature equipment. Such configurations are sufficient when only a few qubits are manipulated. However, scaling the number of qubits to a few 1000s becomes impossible with current technology.
Quantum computer consists of many cryogenically cooled circuits. The solution is to create an integrated readout/control system-on-chip (SoC) integrated circuit (IC) that would be placed in the cryostat (for example at a 4-K stage) near the qubits. By doing so, the number of coaxial cables that carry control signals and readout information from the room-temperature racks of equipment to the qubits can be reduced. In addition to reducing the volume of the equipment, the high-levels of integration afforded by modern CMOS/BiCMOS technologies permits collocation of hundreds of qubit control circuits in one SoC. An SoC affords further flexibility by, for example, enabling frequency or time division multiplexing thereby reusing parts of the SoC. Ultimately, even a classical computer can be located on the SoC for additional flexibility.
The figure shows a typical SoC block diagram. It consists of a readout circuit, drive, and control systems. Many parts are required for the whole system to work. For example the block diagram identifies: low-noise amplifiers (LNAs), I/Q demodulators, variable-gain amplifiers (VGAs), clock generation, analog-to-digital converters (ADCs), and digital-to-analog converters (DACs), etc. All of these have to operate at cryogenic temperatures and consume low power to avoid high thermal loading of the fridge.
Please contact NoiseTech for more information.
