Quantum dial

Fuente: arXiv
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Auteurs principaux: Sah, Aashish, Kundu, Suman, Singh, Priyank, Forsbom, Eemeli, Vadimov, Vasilii, Möttönen, Mikko
Format: Preprint
Publié: 2026
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author Sah, Aashish
Kundu, Suman
Singh, Priyank
Forsbom, Eemeli
Vadimov, Vasilii
Möttönen, Mikko
author_facet Sah, Aashish
Kundu, Suman
Singh, Priyank
Forsbom, Eemeli
Vadimov, Vasilii
Möttönen, Mikko
contents Accurate control of quantum degrees of freedom is promising for sensing, communication, and computing, but building a useful quantum computer faces a central isolation-and-control challenge: qubits must remain well isolated from their environment to preserve coherence, yet also be coupled strongly enough for control, readout, and reset. Existing approaches address this challenge only partially, using separate reset elements, drive schemes, and Purcell filters, often with added complexity and tradeoffs such as heating and crosstalk. Here we introduce and demonstrate a first-generation quantum dial: a device that on demand mediates the coupling of a qubit to selected auxiliary degrees of freedom. Our implementation uses a band-stop filter between a high-coherence transmon qubit and a broadband transmission line, enabling the coupling strength to be tuned by several orders of magnitude on nanosecond timescales without significant Stark shift. In the reset configuration, we reduce the qubit energy relaxation time T1 from >150 $μ$s to about 200 ns and demonstrate reset independent of the initial state. In the control configuration, we obtain 99.99% idle fidelity and 99.9% gate fidelities for 40 ns pulses at about -110 dBm. The same device also enables thermometry of the qubit environment, reaching a noise-equivalent temperature of 0.6 mK/$\sqrt{Hz}$ at 60 mK and approaching the Cramér-Rao bound at higher temperatures. The quantum dial thus offers fast, on-demand switching between isolation and strong coupling, with potential to reduce noise and errors in future quantum processors.
format Preprint
id arxiv_https___arxiv_org_abs_2603_13653
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantum dial
Sah, Aashish
Kundu, Suman
Singh, Priyank
Forsbom, Eemeli
Vadimov, Vasilii
Möttönen, Mikko
Quantum Physics
Accurate control of quantum degrees of freedom is promising for sensing, communication, and computing, but building a useful quantum computer faces a central isolation-and-control challenge: qubits must remain well isolated from their environment to preserve coherence, yet also be coupled strongly enough for control, readout, and reset. Existing approaches address this challenge only partially, using separate reset elements, drive schemes, and Purcell filters, often with added complexity and tradeoffs such as heating and crosstalk. Here we introduce and demonstrate a first-generation quantum dial: a device that on demand mediates the coupling of a qubit to selected auxiliary degrees of freedom. Our implementation uses a band-stop filter between a high-coherence transmon qubit and a broadband transmission line, enabling the coupling strength to be tuned by several orders of magnitude on nanosecond timescales without significant Stark shift. In the reset configuration, we reduce the qubit energy relaxation time T1 from >150 $μ$s to about 200 ns and demonstrate reset independent of the initial state. In the control configuration, we obtain 99.99% idle fidelity and 99.9% gate fidelities for 40 ns pulses at about -110 dBm. The same device also enables thermometry of the qubit environment, reaching a noise-equivalent temperature of 0.6 mK/$\sqrt{Hz}$ at 60 mK and approaching the Cramér-Rao bound at higher temperatures. The quantum dial thus offers fast, on-demand switching between isolation and strong coupling, with potential to reduce noise and errors in future quantum processors.
title Quantum dial
topic Quantum Physics
url https://arxiv.org/abs/2603.13653