Pulsed electron spin resonance spectroscopy in the Purcell regime

Ranjan, V.; Probst, Sebastian; Albanese, B.; Doll, Andrin; Jacquot, O.; Flurin, Emmanuel; Heeres, Reinier; Vion, Denis; Estève, D.; Morton, John J. L.; Bertet, Patrice

doi:10.1016/j.jmr.2019.106662

Cited by 25 publications

(35 citation statements)

References 27 publications

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“…The modulation pattern V 2p (τ ) yields quantitative information about the nature and coupling of the nuclear spins surrounding the electron spin whose echo is measured, and is therefore a useful tool in EPR spectroscopy. When the environmental nuclei have a certain probability p to be of a given isotope with a nuclear spin I = 1/2, and a probability 1 − p to be of an isotope with I = 0, the above formulas are straightforwardly modified (Rowan et al, 1965)…”

Section: Discussion Open Accessmentioning

confidence: 99%

“…and co-workers (Mims et al, 1961;Rowan et al, 1965) for Ce 3+ ions in a CaWO 4 crystal, and was interpreted as being caused by the dipolar interaction of the electronic spin of the Ce 3+ ions with the 183 W nuclear spins of the crystal. The oscillation frequencies appearing in the ESEEM pattern are related to the nuclear spin Larmor frequencies and to their coupling to the https://doi.org/10.5194/mr-2020-10…”

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confidence: 99%

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Hyperfine spectroscopy in a quantum-limited spectrometer

Probst¹,

Zhang²,

Rančić³

et al. 2020

Preprint

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Abstract. We report measurements of electron spin echo envelope modulation (ESEEM) performed at millikelvin temperatures in a custom-built high-sensitivity spectrometer based on superconducting micro-resonators. The high quality factor and small mode volume (down to 0.2 pL) of the resonator allow to probe a small number of spins, down to 5 ⋅ 102. We measure 2-pulse ESEEM on two systems: erbium ions coupled to 183W nuclei in a natural-abundance CaWO4 crystal, and bismuth donors coupled to residual 29Si nuclei in a silicon substrate that was isotopically enriched in the 28Si isotope. We also measure 3- and 5-pulse ESEEM for the bismuth donors in silicon. Quantitative agreement is obtained for both the hyperfine coupling strength of proximal nuclei, and the nuclear spin concentration.

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Section: Discussion Open Accessmentioning

confidence: 99%

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confidence: 99%

Hyperfine spectroscopy in a quantum-limited spectrometer

Probst¹,

Zhang²,

Rančić³

et al. 2020

Preprint

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“…Hz for detecting Hahn echoes emitted by donors in silicon (Ranjan et al, 2020b). A particular feature of these quantum-limited spectrometers is that quantum fluctuations of the microwave field play an important role.…”

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confidence: 99%

“…First, the system output noise is governed by these quantum fluctuations, with negligible thermal noise contribution. Second, quantum fluctuations also impact spin dynamics by triggering spontaneous emission of microwave photons at a rate P = 4g 2 /κ, g being the spin-photon coupling (Bienfait et al, 2016;Eichler et al, 2017;Ranjan et al, 2020a). This Purcell effect forbids T 1 from becoming prohibitively long since it is at most equal to −1 P , making spin detection with a reasonable repetition rate possible even at the lowest temperatures.…”

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confidence: 99%

Hyperfine spectroscopy in a quantum-limited spectrometer

Probst

Zhang

Rančić³

et al. 2020

Magn. Reson.

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Abstract. We report measurements of electron-spin-echo envelope modulation (ESEEM) performed at millikelvin temperatures in a custom-built high-sensitivity spectrometer based on superconducting micro-resonators. The high quality factor and small mode volume (down to 0.2 pL) of the resonator allow us to probe a small number of spins, down to 5×102. We measure two-pulse ESEEM on two systems: erbium ions coupled to 183W nuclei in a natural-abundance CaWO4 crystal and bismuth donors coupled to residual 29Si nuclei in a silicon substrate that was isotopically enriched in the 28Si isotope. We also measure three- and five-pulse ESEEM for the bismuth donors in silicon. Quantitative agreement is obtained for both the hyperfine coupling strength of proximal nuclei and the nuclear-spin concentration.

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“…Spin simulation. The simulation of the dynamics of the spin ensemble weakly coupled to the intra-cavity field consists in numerical solution of the system semi-classical equation of motion, as described in [32]. The system of differential equations is solved for M values of coupling g and the results are averaged using ρ(g) as weighting function.…”

Section: Supplementary Informationmentioning

confidence: 99%

Radiative cooling of a spin ensemble

et al. 2020

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Physical systems reach thermal equilibrium through energy exchange with their environment, and for spins in solids the relevant environment is almost always the host lattice in which they sit. However, recent studies motivated by observations from Purcell showed how coupling to a cavity can become the dominant form of relaxation for spins, given suitably strong spin-cavity coupling. In this regime, the cavity electromagnetic field takes over from the lattice as the dominant environment, inviting the prospect of controlling the spin temperature independently from that of the lattice, by engineering a suitable cavity field. Here, we report on precisely such control over spin temperature, illustrating a novel and universal method of electron spin hyperpolarisation. By switching the cavity input between loads at different temperatures we can control the electron spin polarisation, cooling it below the lattice temperature. Our demonstration uses donor spins in silicon coupled to a superconducting micro-resonator and we observe an increase of spin polarisation of over a factor of two. This approach provides general route to signal enhancement in electron spin resonance, or indeed nuclear magnetic resonance through dynamical nuclear spin polarisation (DNP). When a physical system is coupled to several reservoirs at different temperatures, it equilibrates at an intermediate temperature which depends on the strength with which it is coupled to each bath. An electron spin in a solid is coupled to two different reservoirs: phonons in its host lattice, and microwave photons in its electromagnetic environment. The strength of this coupling is characterized by the rate at which the spin, of Larmor frequency ω spin , relaxes by spontaneously emitting a quantum of energy ω spin into each bath. In usual magnetic resonance experiments [5], the spin-lattice relaxation rate Γ phon is many orders of magnitude larger than the radiative relaxation rate Γ phot , so that the spin temperature T spin is determined by the sample temperature T phon regardless of the temperature of the microwave photons T phot .The strength of radiative relaxation can however be enhanced by coupling the spins resonantly to one mode of a microwave resonator of frequency ω 0 = ω spin , as discovered by Purcell [2,6,7]. The coupling strength is then given by Γ phot = 4g 2 /κ, g being the spin-photon coupling constant and κ the resonator mode relaxation rate. Superconducting micro-resonators can be designed with a small mode volume, which increases g, while retaining a high quality factor, which reduces κ. This makes it possible to reach the Purcell regime defined by Γ phot Γ phon , as demonstrated in recent experiments [1]. In this regime, T spin should thus be equal to T phot and no longer to T phon , and electron spin hyperpolarisation should be possible by cooling the microwave field down to a temperature T phot T phon . The simplest way to do so is to connect the resonator input to a cold 50 Ω resistor, as shown in Fig. 1a. As long as the coupling rate of th...

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Pulsed electron spin resonance spectroscopy in the Purcell regime

Cited by 25 publications

References 27 publications

Hyperfine spectroscopy in a quantum-limited spectrometer

Hyperfine spectroscopy in a quantum-limited spectrometer

Hyperfine spectroscopy in a quantum-limited spectrometer

Radiative cooling of a spin ensemble

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