Realization of Constant-Depth Fan-Out with Real-Time Feedforward on a Superconducting Quantum Processor

Fuente: arXiv
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Autori principali: Song, Yongxin, Beltrán, Liberto, Besedin, Ilya, Kerschbaum, Michael, Pechal, Marek, Swiadek, François, Hellings, Christoph, Zanuz, Dante Colao, Flasby, Alexander, Besse, Jean-Claude, Wallraff, Andreas
Natura: Preprint
Pubblicazione: 2024
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author Song, Yongxin
Beltrán, Liberto
Besedin, Ilya
Kerschbaum, Michael
Pechal, Marek
Swiadek, François
Hellings, Christoph
Zanuz, Dante Colao
Flasby, Alexander
Besse, Jean-Claude
Wallraff, Andreas
author_facet Song, Yongxin
Beltrán, Liberto
Besedin, Ilya
Kerschbaum, Michael
Pechal, Marek
Swiadek, François
Hellings, Christoph
Zanuz, Dante Colao
Flasby, Alexander
Besse, Jean-Claude
Wallraff, Andreas
contents When using unitary gate sequences, the growth in depth of many quantum circuits with output size poses significant obstacles to practical quantum computation. The quantum fan-out operation, which reduces the circuit depth of quantum algorithms such as the quantum Fourier transform and Shor's algorithm, is an example that can be realized in constant depth independent of the output size. Here, we demonstrate a quantum fan-out gate with real-time feedforward on up to four output qubits using a superconducting quantum processor. By performing quantum state tomography on the output states, we benchmark our gate with input states spanning the entire Bloch sphere. We decompose the output-state error into a set of independently characterized error contributions. We extrapolate our constant-depth circuit to offer a scaling advantage compared to the unitary fan-out sequence beyond 25 output qubits with feedforward control, or beyond 17 output qubits if the classical feedforward latency is negligible. Our work highlights the potential of mid-circuit measurements combined with real-time conditional operations to improve the efficiency of complex quantum algorithms.
format Preprint
id arxiv_https___arxiv_org_abs_2409_06989
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Realization of Constant-Depth Fan-Out with Real-Time Feedforward on a Superconducting Quantum Processor
Song, Yongxin
Beltrán, Liberto
Besedin, Ilya
Kerschbaum, Michael
Pechal, Marek
Swiadek, François
Hellings, Christoph
Zanuz, Dante Colao
Flasby, Alexander
Besse, Jean-Claude
Wallraff, Andreas
Quantum Physics
When using unitary gate sequences, the growth in depth of many quantum circuits with output size poses significant obstacles to practical quantum computation. The quantum fan-out operation, which reduces the circuit depth of quantum algorithms such as the quantum Fourier transform and Shor's algorithm, is an example that can be realized in constant depth independent of the output size. Here, we demonstrate a quantum fan-out gate with real-time feedforward on up to four output qubits using a superconducting quantum processor. By performing quantum state tomography on the output states, we benchmark our gate with input states spanning the entire Bloch sphere. We decompose the output-state error into a set of independently characterized error contributions. We extrapolate our constant-depth circuit to offer a scaling advantage compared to the unitary fan-out sequence beyond 25 output qubits with feedforward control, or beyond 17 output qubits if the classical feedforward latency is negligible. Our work highlights the potential of mid-circuit measurements combined with real-time conditional operations to improve the efficiency of complex quantum algorithms.
title Realization of Constant-Depth Fan-Out with Real-Time Feedforward on a Superconducting Quantum Processor
topic Quantum Physics
url https://arxiv.org/abs/2409.06989