Superconducting qubit–oscillator circuit beyond the ultrastrong-coupling regime

Fumiki Yoshihara, Tomoko Fuse, Sahel Ashhab, Kosuke Kakuyanagi, Shiro Saito, Kouichi Semba

Research output: Contribution to journalArticle

188 Citations (Scopus)

Abstract

The interaction between an atom and the electromagnetic field inside a cavity has played a crucial role in developing our understanding of light–matter interaction, and is central to various quantum technologies, including lasers and many quantum computing architectures. Superconducting qubits have allowed the realization of strong and ultrastrong coupling between artificial atoms and cavities. If the coupling strength g becomes as large as the atomic and cavity frequencies (Δ and ωo, respectively), the energy eigenstates including the ground state are predicted to be highly entangled. There has been an ongoing debate over whether it is fundamentally possible to realize this regime in realistic physical systems. By inductively coupling a flux qubit and an LC oscillator via Josephson junctions, we have realized circuits with g/ωo ranging from 0.72 to 1.34 and g/Δ ≫ 1. Using spectroscopy measurements, we have observed unconventional transition spectra that are characteristic of this new regime. Our results provide a basis for ground-state-based entangled pair generation and open a new direction of research on strongly correlated light–matter states in circuit quantum electrodynamics.

Original languageEnglish
JournalNature Physics
DOIs
Publication statusAccepted/In press - 10 Oct 2016

Fingerprint

cavities
ground state
quantum computation
quantum electrodynamics
Josephson junctions
atoms
eigenvectors
electromagnetic fields
oscillators
interactions
spectroscopy
lasers
energy

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Superconducting qubit–oscillator circuit beyond the ultrastrong-coupling regime. / Yoshihara, Fumiki; Fuse, Tomoko; Ashhab, Sahel; Kakuyanagi, Kosuke; Saito, Shiro; Semba, Kouichi.

In: Nature Physics, 10.10.2016.

Research output: Contribution to journalArticle

Yoshihara, Fumiki ; Fuse, Tomoko ; Ashhab, Sahel ; Kakuyanagi, Kosuke ; Saito, Shiro ; Semba, Kouichi. / Superconducting qubit–oscillator circuit beyond the ultrastrong-coupling regime. In: Nature Physics. 2016.
@article{cf42855b40a244a98dc7ad051e769e21,
title = "Superconducting qubit–oscillator circuit beyond the ultrastrong-coupling regime",
abstract = "The interaction between an atom and the electromagnetic field inside a cavity has played a crucial role in developing our understanding of light–matter interaction, and is central to various quantum technologies, including lasers and many quantum computing architectures. Superconducting qubits have allowed the realization of strong and ultrastrong coupling between artificial atoms and cavities. If the coupling strength g becomes as large as the atomic and cavity frequencies (Δ and ωo, respectively), the energy eigenstates including the ground state are predicted to be highly entangled. There has been an ongoing debate over whether it is fundamentally possible to realize this regime in realistic physical systems. By inductively coupling a flux qubit and an LC oscillator via Josephson junctions, we have realized circuits with g/ωo ranging from 0.72 to 1.34 and g/Δ ≫ 1. Using spectroscopy measurements, we have observed unconventional transition spectra that are characteristic of this new regime. Our results provide a basis for ground-state-based entangled pair generation and open a new direction of research on strongly correlated light–matter states in circuit quantum electrodynamics.",
author = "Fumiki Yoshihara and Tomoko Fuse and Sahel Ashhab and Kosuke Kakuyanagi and Shiro Saito and Kouichi Semba",
year = "2016",
month = "10",
day = "10",
doi = "10.1038/nphys3906",
language = "English",
journal = "Nature Physics",
issn = "1745-2473",
publisher = "Nature Publishing Group",

}

TY - JOUR

T1 - Superconducting qubit–oscillator circuit beyond the ultrastrong-coupling regime

AU - Yoshihara, Fumiki

AU - Fuse, Tomoko

AU - Ashhab, Sahel

AU - Kakuyanagi, Kosuke

AU - Saito, Shiro

AU - Semba, Kouichi

PY - 2016/10/10

Y1 - 2016/10/10

N2 - The interaction between an atom and the electromagnetic field inside a cavity has played a crucial role in developing our understanding of light–matter interaction, and is central to various quantum technologies, including lasers and many quantum computing architectures. Superconducting qubits have allowed the realization of strong and ultrastrong coupling between artificial atoms and cavities. If the coupling strength g becomes as large as the atomic and cavity frequencies (Δ and ωo, respectively), the energy eigenstates including the ground state are predicted to be highly entangled. There has been an ongoing debate over whether it is fundamentally possible to realize this regime in realistic physical systems. By inductively coupling a flux qubit and an LC oscillator via Josephson junctions, we have realized circuits with g/ωo ranging from 0.72 to 1.34 and g/Δ ≫ 1. Using spectroscopy measurements, we have observed unconventional transition spectra that are characteristic of this new regime. Our results provide a basis for ground-state-based entangled pair generation and open a new direction of research on strongly correlated light–matter states in circuit quantum electrodynamics.

AB - The interaction between an atom and the electromagnetic field inside a cavity has played a crucial role in developing our understanding of light–matter interaction, and is central to various quantum technologies, including lasers and many quantum computing architectures. Superconducting qubits have allowed the realization of strong and ultrastrong coupling between artificial atoms and cavities. If the coupling strength g becomes as large as the atomic and cavity frequencies (Δ and ωo, respectively), the energy eigenstates including the ground state are predicted to be highly entangled. There has been an ongoing debate over whether it is fundamentally possible to realize this regime in realistic physical systems. By inductively coupling a flux qubit and an LC oscillator via Josephson junctions, we have realized circuits with g/ωo ranging from 0.72 to 1.34 and g/Δ ≫ 1. Using spectroscopy measurements, we have observed unconventional transition spectra that are characteristic of this new regime. Our results provide a basis for ground-state-based entangled pair generation and open a new direction of research on strongly correlated light–matter states in circuit quantum electrodynamics.

UR - http://www.scopus.com/inward/record.url?scp=84990877459&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84990877459&partnerID=8YFLogxK

U2 - 10.1038/nphys3906

DO - 10.1038/nphys3906

M3 - Article

AN - SCOPUS:84990877459

JO - Nature Physics

JF - Nature Physics

SN - 1745-2473

ER -