Photon-Assisted Shot Noise in Graphene in the Terahertz Range

Parmentier, François; Loli, L. N. Serkovic; Roulleau, Preden; Glattli, Christian

doi:10.1103/physrevlett.116.227401

Cited by 20 publications

(22 citation statements)

References 33 publications

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“…The studied systems cover different new features of photon-assisted quantum transport occurring into the GHz and THz frequency spectra. Actually, measurements of the quantum shot noise in a graphene nanoribbon subjected to electromagnetic THz radiation were recently reported [27], indicating that the studied bilayer graphene flake system may be realized and proposed as THz frequency detector devices.…”

Section: A)-(d) the Weighted Spin Polarization Exhibits The Same Behmentioning

confidence: 99%

Photon-assisted transport in bilayer graphene flakes

et al. 2017

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The electronic conductance of graphene-based bilayer flake systems reveal different quantum interference effects, such as Fabry-Pérot resonances and sharp Fano antiresonances on account of competing electronic paths through the device. These properties may be exploited to obtain spinpolarized currents when the same nanostructure is deposited above a ferromagnetic insulator. Here we study how the spin-dependent conductance is affected when a time-dependent gate potential is applied to the bilayer flake. Following a Tien-Gordon formalism we explore how to modulate the transport properties of such systems via appropriate choices of the ac-field gate parameters. The presence of the oscillating field opens the possibility of tuning the original antiresonances for a large set of field parameters. We show that interference patterns can be partially or fully removed by the time-dependent gate voltage. The results are reflected in the corresponding weighted spin polarization which can reach maximum values for a given spin component. We found that differential conductance maps as functions of bias and gate potentials show interference patterns for different ac-field parameter configurations. The proposed bilayer graphene flake systems may be used as a frequency detector in the THz range.

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Section: A)-(d) the Weighted Spin Polarization Exhibits The Same Behmentioning

confidence: 99%

Photon-assisted transport in bilayer graphene flakes

et al. 2017

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“…[88,91], the greater and lesser Green's functions were expressed in terms of the S α matrices following a line integral of the Kadanof-Baym equations in the two-time plane, and these are given in Eq. (25). We thus have explicit formulas for all terms which appear in the two-time correlation function, which may be evaluated numerically in the (t 1 ,t 2 ) plane as follows:…”

Section: Time-dependent Model and The Wblamentioning

confidence: 99%

“…Recent measurements of shot noise in graphene irradiated by THz fields showed an enhancement of the shot noise due to the excitation of electron-hole pairs in the sample [25].…”

Section: Introductionmentioning

confidence: 99%

Partition-free theory of time-dependent current correlations in nanojunctions in response to an arbitrary time-dependent bias

2017

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Working within the nonequilibrium Green's function formalism, a formula for the two-time current correlation function is derived for the case of transport through a nanojunction in response to an arbitrary time-dependent bias. The one-particle Hamiltonian and the wide-band limit approximation are assumed, enabling us to extract all necessary Green's functions and self-energies for the system, extending the analytic work presented previously [Ridley et al., Phys. Rev. B 91, 125433 (2015)]. We show that our expression for the two-time correlation function generalizes the Büttiker theory of shot and thermal noise on the current through a nanojunction to the time-dependent bias case including the transient regime following the switch-on. Transient terms in the correlation function arise from an initial state that does not assume (as is usually done) that the system is initially uncoupled, i.e., our approach is partition free. We show that when the bias loses its time dependence, the long-time limit of the current correlation function depends on the time difference only, as in this case an ideal steady state is reached. This enables derivation of known results for the single-frequency power spectrum and for the zero-frequency limit of this power spectrum. In addition, we present a technique which facilitates fast calculations of the transient quantum noise, valid for arbitrary temperature, time, and voltage scales. We apply this formalism to a molecular wire system for both dc and ac biases, and find a signature of the traversal time for electrons crossing the wire in the time-dependent cross-lead current correlations.

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“…55. In the context of graphene, photonassisted shot noise was recently measured in the diffusive electron transport regime 56 . It was shown that shot noise signatures of radiation in this system could be extended to the higher THz frequency range.…”

Section: Introductionmentioning

confidence: 99%

Shot noise in a harmonically driven ballistic graphene transistor

2017

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We study time-dependent electron transport and quantum noise in a ballistic graphene field effect transistor driven by an ac gate potential. The non-linear response to the ac signal is computed through Floquet theory for scattering states and Landauer-Büttiker theory for charge current and its fluctuations. Photon-assisted excitation of a quasibound state in the top-gate barrier leads to resonances in transmission that strongly influence the noise properties. For strong doping of graphene under source and drain contacts, when electrons are transmitted through the channel via evanescent waves, the resonance leads to a substantial suppression of noise. The Fano factor is then reduced well below the pseudo-diffusive value, F < 1/3, also for strong ac drive. The good signal-to-noise ratio (small Fano factor) on resonance suggests that the device is a good candidate for high-frequency (THz) radiation detection. We show analytically that Klein tunneling (total suppression of back-reflection) persists for perpendicular incidence also when the barrier is driven harmonically. Although the transmission is inelastic and distributed among sideband energies, a sum rule leads to total suppression of shot noise.

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Photon-Assisted Shot Noise in Graphene in the Terahertz Range

Cited by 20 publications

References 33 publications

Photon-assisted transport in bilayer graphene flakes

Photon-assisted transport in bilayer graphene flakes

Partition-free theory of time-dependent current correlations in nanojunctions in response to an arbitrary time-dependent bias

Shot noise in a harmonically driven ballistic graphene transistor

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