Quantum analog-to-digital and digital-to-analog conversion (8 pages)

Akira SaiToh

Benjamin M. Rabinovici

DARREN K. BROCK, S.S. Martinet, Mark F. Bocko +1 more

Successful utilization of the quasi one-junction SQUID (QOS) as a signal comparator for analog-to-digital conversion (ADC) has been demonstrated by several groups, This idea is extended to show how similar comparators can be integrated into an all rapid single flux quantum (RSFQ) digital architecture. Comparators are interrogated by SFQ sampling pulses and in turn give output according to the RSFQ convention. One- and two-bit ADC's have been simulated, fabricated and tested at low speed. Total performance of these devices is estimated within the framework of a multiple bit parallel flash ADC architecture.>

Yuan Liu, John M. Martyn, Jasmine Sinanan-Singh +3 more

Signal processing stands as a pillar of classical computation and modern information technology, applicable to both analog and digital signals. Recently, advancements in quantum information science have suggested that quantum signal processing (QSP) can enable more powerful signal processing capabilities. However, the developments in QSP have primarily leverageddigitalquantum resources, such as discrete-variable (DV) systems like qubits, rather thananalogquantum resources, such as continuous-variable (CV) systems like quantum oscillators. Consequently, there remains a gap in understanding how signal processing can be performed on hybrid CV-DV quantum computers. Here we address this gap by developing a new paradigm of mixed analog-digital QSP. We demonstrate the utility of this paradigm by showcasing how it naturally enables analog-digital conversion of quantum signals— specifically, the transfer of states between DV and CV quantum systems. We then show that such quantum analog-digital conversion enables new implementations of quantum algorithms on CV-DV hardware. This is exemplified by realizing the quantum Fourier transform of a state encoded on qubits via the free-evolution of a quantum oscillator, albeit with a runtime exponential in the number of qubits due to information theoretic arguments. Collectively, this work marks a significant step forward in hybrid CV-DV quantum computation, providing a foundation for scalable analog-digital signal processing on quantum processors.

Asier Galicia Martínez

Mikel Sanz