Electron-phonon instability in graphene revealed by global and local noise probes

Andersen, Trond I.; Dwyer, Bo; Sanchez-Yamagishi, Javier; Rodriguez-Nieva, Joaquin F.; Agarwal, Kartiek; Watanabe, Kenji; Taniguchi, Takashi; Demler, Eugene; Kim, Philip; Park, Hongkun; Lukin, Mikhail D.

doi:10.1126/science.aaw2104

Cited by 62 publications

(46 citation statements)

References 57 publications

(30 reference statements)

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“…Our results may readily be generalized to other physical mechanisms of wave emission, for example analogues of the Cherenkov effect [83][84][85][86] outside of electrodynamics, as in Bose-Einstein condensates. Similar effects can be explored with any photonic quasiparticle 87 , and even with sound waves, and phonon waves in solids 88 , which all have the same underlying quantum nature and must have exact analogous phenomena.…”

Section: Discussionmentioning

confidence: 95%

The coherence of light is fundamentally tied to the quantum coherence of the emitting particle

et al. 2021

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Coherent emission of light by free charged particles is believed to be successfully captured by classical electromagnetism in all experimental settings. However, recent advances triggered fundamental questions regarding the role of the particle wave function in these processes. Here, we find that even in seemingly classical experimental regimes, light emission is fundamentally tied to the quantum coherence and correlations of the emitting particle. We use quantum electrodynamics to show how the particle’s momentum uncertainty determines the optical coherence of the emitted light. We find that the temporal duration of Cherenkov radiation, envisioned for almost a century as a shock wave of light, is limited by underlying entanglement between the particle and light. Our findings enable new capabilities in electron microscopy for measuring quantum correlations of shaped electrons. Last, we propose new Cherenkov detection schemes, whereby measuring spectral photon autocorrelations can unveil the wave function structure of any charged high-energy particle.

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Section: Discussionmentioning

confidence: 95%

The coherence of light is fundamentally tied to the quantum coherence of the emitting particle

et al. 2021

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“…Similar measurement of magnetic noise spectrum with NV centers also revealed the chemical potentials [45]. Recently, the capability of detecting electronic correlated phenomena and studying the transport behavior is also proposed [46,47], where even more directions pointed out such as the observation of localization in 2D electron gases [46]. Our protocol provides a tool to perform a 3D detection of these phenomena such as excitation in spin-wave [41,42] and skyrmions [48], as well as the 3D analysis of the electronic transport properties [46].…”

Section: Discussionmentioning

confidence: 79%

Nanoscale vector AC magnetometry with a single nitrogen-vacancy center in diamond

Wang,

Liu,

Zhu

et al. 2021

Preprint

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Detection of AC magnetic fields at the nanoscale is critical in applications ranging from fundamental physics to materials science. Isolated quantum spin defects, such as the nitrogen-vacancy center in diamond, can achieve the desired spatial resolution with high sensitivity. Still, vector AC magnetometry currently relies on using different orientations of an ensemble of sensors, with degraded spatial resolution, and a protocol based on a single NV is lacking. Here we propose and experimentally demonstrate a protocol that exploits a single NV to reconstruct the vectorial components of an AC magnetic field by tuning a continuous driving to distinct resonance conditions. We map the spatial distribution of an AC field generated by a copper wire on the surface of the diamond. The proposed protocol combines high sensitivity, broad dynamic range, and sensitivity to both coherent and stochastic signals, with broad applications in condensed matter physics, such as probing spin fluctuations.

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“…There is however, an alternative way to probe linear response functions that does not require actively applying external perturbations on the system, but instead to monitor its fluctuations since the fluctuationdissipation theorem dictates that these are governed by the dissipative part of the same linear response susceptibilities. This is the key idea behind the technique of magnetic noise spectroscopy of nitrogen-vacancy center spin qubits [14], which is emerging as a powerful tool to study current and spin correlations of diverse condensed matter systems [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

The universal shear conductivity of Fermi liquids and spinon Fermi surface states and its detection via spin qubit noise magnetometry

Khoo,

Pientka,

Sodemann

2021

Preprint

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We demonstrate a remarkable property of metallic Fermi liquids: the transverse conductivity assumes a universal value in the quasi-static (ω → 0) limit for wavevectors q in the regime l −1 mfp ≪ q ≪ pF, where l mfp is the mean free path and pF is the Fermi momentum. This value is (e 2 /h)RFS/q in two dimensions (2D), where RFS measures the local radius of curvature of the Fermi surface in momentum space. Even more surprisingly, we find that U(1) spin liquids with a spinon Fermi surface have the same universal transverse conductivity. This means such spin liquids behave effectively as metals in this regime, even though they appear insulating in standard transport experiments. Moreover, we show that transverse current fluctuations result in a universal low-frequency magnetic noise that can be directly probed by a spin qubit, such as a nitrogen-vacancy center in diamond, placed at a distance z above of the 2D metal or spin liquid. Specifically the magnetic noise is given by CωPFS/z, where PFS is the perimeter of the Fermi surface in momentum space and C is a combination of fundamental constants of nature. Therefore these observables are controlled purely by the geometry of the Fermi surface and are independent of kinematic details of the quasiparticles, such as their effective mass and interactions. This behavior can be used as a new technique to measure the size of the Fermi surface of metals and as a smoking gun probe to pinpoint the presence of the elusive spinon Fermi surface in two-dimensional systems. We estimate that this universal regime is within reach of current nitrogen-vacancy center spectroscopic techniques for several spinon Fermi surface candidate materials.

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Electron-phonon instability in graphene revealed by global and local noise probes

Cited by 62 publications

References 57 publications

The coherence of light is fundamentally tied to the quantum coherence of the emitting particle

The coherence of light is fundamentally tied to the quantum coherence of the emitting particle

Nanoscale vector AC magnetometry with a single nitrogen-vacancy center in diamond

The universal shear conductivity of Fermi liquids and spinon Fermi surface states and its detection via spin qubit noise magnetometry

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