Electron spin resonance with up to 20 spin sensitivity measured using a superconducting flux qubit

Budoyo, R.P.; Kakuyanagi, Kosuke; Toida, Hiraku; Matsuzaki, Yuichiro; Saito, Shiro

doi:10.1063/1.5144722

Cited by 26 publications

(23 citation statements)

References 33 publications

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“…Dephasing during the sensing process is a main obstacle for quantum-enhanced sensing. In particular, it is known that time-inhomogeneous dephasing (non-Markovian dephasing) is relevant for magnetometry using solid-state systems, e.g., nitrogen-vacancy centers [48,[50][51][52] and flux qubits [53][54][55][56][57]. Here we explain the effect of time-inhomogeneous dephasing during the sensing process.…”

Section: Dephasingmentioning

confidence: 93%

Quantum metrology based on symmetry-protected adiabatic transformation: imperfection, finite time duration, and dephasing

Hatomura

Yoshinaga²,

Matsuzaki³

et al. 2022

New J. Phys.

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The aim of quantum metrology is to estimate target parameters as precisely as possible. In this paper, we consider quantum metrology based on symmetry-protected adiabatic transformation. We introduce a ferromagnetic Ising model with a transverse field as a probe and consider the estimation of a longitudinal field. Without the transverse field, the ground state of the probe is given by the Greenberger-Horne-Zeilinger state, and thus the Heisenberg limit estimation of the longitudinal field can be achieved through parity measurement. In our scheme, full information of the longitudinal field encoded on parity is exactly mapped to global magnetization by symmetry-protected adiabatic transformation, and thus the parity measurement can be replaced with global magnetization measurement. Moreover, this scheme requires neither accurate control of individual qubits nor that of interaction strength. We discuss the effects of the finite transverse field and nonadiabatic transitions as imperfection of adiabatic transformation. By taking into account finite time duration for state preparation, sensing, and readout, we also compare performance of the present scheme with a classical scheme in the absence and presence of dephasing.

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Section: Dephasingmentioning

confidence: 93%

Quantum metrology based on symmetry-protected adiabatic transformation: imperfection, finite time duration, and dephasing

Hatomura

Yoshinaga²,

Matsuzaki³

et al. 2022

New J. Phys.

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“…For this purpose, we could use a waveguide [10], a frequency tunable resonator [11], or a direct current-superconducting quantum interference device (dcSQUID) [2,12]. Among these approaches, a superconducting flux qubit (FQ) is promising and has already achieved a sensitivity of 20 spins/Hz 1/2 with a sensing volume of 6 fl for the ESR [13].…”

Section: Introductionmentioning

confidence: 99%

Polarizing electron spins with a superconducting flux qubit

Kukita,

Ookane,

Matsuzaki

et al. 2021

Preprint

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Electron spin resonance (ESR) is a useful tool to investigate properties of materials in magnetic fields where high spin polarization of target electron spins is required in order to obtain high sensitivity. However, the smaller magnetic fields becomes, the more difficult high polarization is passively obtained by thermalization. Here, we propose to employ a superconducting flux qubit (FQ) to polarize electron spins actively. We have to overcome a large energy difference between the FQ and electron spins for efficient energy transfer among them. For this purpose, we adopt a spin-lock technique on the FQ where the Rabi frequency associated with the spin-locking can match the resonance (Larmor) one of the electron spins. We find that adding dephasing on the spins is beneficial to obtain high polarization of them, because otherwise the electron spins are trapped in dark states that cannot be coupled with the FQ. We show that our scheme can achieve high polarization of electron spins in realistic experimental conditions.

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“…Introduction.-Quantum metrology with entangled resources has been shown to reach the Heisenberg limit of sensitivity with respect to the number of qubits [1][2][3][4][5][6]. It may provide significant improvements for versatile applications such as atomic-frequency [7,8] and electron-spinresonance measurements [9][10][11], magnetometry [12][13][14][15][16][17][18][19], thermometry [20][21][22], and electrometer [23,24].…”

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confidence: 99%

“…Intractable noise characterization leads to inaccurate theoretical models and induces systematic errors in estimations. In practice, systematic errors are fatal to quantum metrology because they cannot be reduced even if the number of samples is increased, thus seriously limiting any sensitivity improvement [9,45]. Despite that systematic errors are typically present in experiments, there is as yet no general approach to dealing them, although some studies have tackled specific scenarios [46][47][48][49].…”

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confidence: 99%

“…FQs are promising for both quantum metrology and quantum computation [68][69][70] because of their long coherence time [71]. Moreover, FQs are advantageous for quantum metrology as they have a strong coupling with magnetic fields and are therefore suitable for quantum magnetic field sensing [9,11,72]. For quantum computation, since FQs are artificial atoms, there are many degrees of freedom for circuit design, which enables us to build a universal gate set with high fidelity and scalability [73,74].…”

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confidence: 99%

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