  On superconducting architectures, the state of a qubit is manipulated by
using microwave pulses. Typically, the pulses are stored in the waveform memory
and then streamed to the Digital-to-Analog Converter (DAC) to synthesize the
gate operations. The waveform memory requires tens of gigabytes per second of
bandwidth to manipulate the qubit. Unfortunately, the required memory bandwidth
grows linearly with the number of qubits. As a result, the bandwidth demand
limits the number of qubits we can control concurrently. For example, on
current RFSoCs-based qubit control platforms, we can control less than 40
qubits. In addition, the high memory bandwidth for cryogenic ASIC controllers
designed to operate within a tight power budget translates to significant power
dissipation, thus limiting scalability. In this paper, we show that waveforms
are highly compressible, and we leverage this property to enable a scalable and
efficient microarchitecture COMPAQT - Compressed Waveform Memory Architecture
for Qubit Control. Waveform memory is read-only and COMPAQT leverages this to
compress waveforms at compile time and store the compressed waveform in the
on-chip memory. To generate the pulse, COMPAQT decompresses the waveform at
runtime and then streams the decompressed waveform to the DACs. Using the
hardware-efficient discrete cosine transform, COMPAQT can achieve, on average,
5x increase in the waveform memory bandwidth, which can enable 5x increase in
the total number of qubits controlled in an RFSoC setup. Moreover, COMPAQT
microarchitecture for cryogenic CMOS ASIC controllers can result in a 2.5x
power reduction over uncompressed baseline. We also propose an adaptive
compression scheme to further reduce the power consumed by the decompression
engine, enabling up to 4x power reduction. We see less than 0.1% degradation in
fidelity when using COMPAQT despite using a lossy compression scheme.
