Shot noise in mesoscopic conductors

Blanter, Ya. M.; Büttiker, Μ.

doi:10.1016/s0370-1573(99)00123-4

Cited by 2,516 publications

(2,373 citation statements)

References 300 publications

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“…For example, it has been used to observe the quantization of electrical charge in shot noise measurements [63], the observation of fractional charges in fractional quantum Hall systems [64][65][66], and was used to characterize prethermalization in an ultracold atomic setup [47,67,68]. Here we determine the FCS of the staggered magnetization operatorm z = 1 N i (−1) i 1 S S z i from an ab initio quantum Monte Carlo simulation of the antiferromagnetic Heisenberg model…”

Section: System Calibrationsmentioning

confidence: 99%

A cold-atom Fermi–Hubbard antiferromagnet

Mazurenko

Chiu

et al. 2017

Nature

751

689

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Many exotic phenomena in strongly correlated electron systems emerge from the interplay between spin and motional degrees of freedom [1, 2]. For example, doping an antiferromagnet gives rise to interesting phases including pseudogap states and high-temperature superconductors [3]. A promising route towards achieving a complete understanding of these materials begins with analytic and computational analysis of simplified models. Quantum simulation has recently emerged as a complementary approach towards understanding these models [4][5][6][7][8]. Ultracold fermions in optical lattices offer the potential to answer open questions on the lowtemperature regime of the doped Hubbard model [9][10][11], which is thought to capture essential aspects of the cuprate superconductor phase diagram but is numerically intractable in that parameter regime. Already, Mott-insulating phases and short-range antiferromagnetic correlations have been observed, but temperatures were too high to create an antiferromagnet [12][13][14][15]. A new perspective is afforded by quantum gas microscopy [16][17][18][19][20][21][22][23][24][25][26][27][28], which allows readout of magnetic correlations at the site-resolved level [25][26][27][28]. Here we report the realization of an antiferromagnet in a repulsively interacting Fermi gas on a 2D square lattice of approximately 80 sites. Using site-resolved imaging, we detect (finite-size) antiferromagnetic long-range order (LRO) through the development of a peak in the spin structure factor and the divergence of the correlation length that reaches the size of the system. At our lowest temperature of T/t = 0.25(2) we find strong order across the entire sample, where the staggered magnetization approaches the ground-state value. Our experimental platform enables doping away from half filling, where pseudogap states and stripe ordering are expected, but theoretical methods become numerically intractable. In this regime we find that the antiferromagnetic LRO persists to hole dopings of about 15%, providing a guideline for computational methods. Our results demonstrate that quantum gas microscopy of ultracold fermions in optical lattices can now address open questions on the low-temperature Hubbard model.The Hubbard Hamiltonian is a fundamental model for spinful lattice electrons describing a competition between kinetic energy t and interaction energy U [29]. In the limiting case of half-filling (average one particle per site) and dominant interactions (U/t 1) the Hubbard model maps to the Heisenberg model [1]. There, the exchange energy J = 4t 2 /U can give rise to antiferromagnetically ordered states at low temperatures [30]. This order persists for all finite U/t, where charge fluctuations reduce the ordering strength [31]. Away from half-filling, the coupling between motional and spin degrees of freedom is expected to give rise to a rich many-body phase diagram (see Fig. 1a), which is challenging to understand theoretically due to the fermion sign problem [32]. Even so, in the thermodynamic limit com...

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Section: System Calibrationsmentioning

confidence: 99%

A cold-atom Fermi–Hubbard antiferromagnet

Mazurenko

Chiu

et al. 2017

Nature

751

689

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“…4 This heating effect will become less important at large bias because the shot noise will eventually take over fully and, thus, the value of F saturates. Other mechanisms that can change the measured Fano factor include electron-electron interactions [24,5], incoherent scattering [9], and thermal gradients in the metallic lead due to heat diffusion [25]. However, the first two processes should lead to F = 1/3 as V bias → 0 and higher F in the high bias regime (i.e.…”

Section: Results On Shot Noisementioning

confidence: 99%

“…When the system is biased, shot noise appears due to discreteness of charge [5] and these current fluctuations for a single channel are given by (δI) 2 = 2e I (1 − τ ). The total noise power spectrum for a multichannel conductor is then obtained by summing over all N transmission eigenchannels:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Shot noise measurements in graphene

Danneau

Craciun

et al. 2009

Solid State Communications

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a b s t r a c tWe have investigated shot noise at microwave frequencies in wide-aspect-ratio graphene sheets in the temperature range of 4.2-30 K. We find that for our short (L < 300 nm) graphene samples with width over length ratio W /L > 3, the Fano factor F reaches a maximum F ∼ 1/3 at the Dirac point and that it decreases substantially with increasing charge density. Our results agree with the theoretical prediction that electrical transport at the Dirac point is governed by evanescent electronic states.

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“…[30] assumes that the system is strongly coupled to the leads, that the motion of the electrons through system and controller is phase coherent and that electron-electron interactions can be neglected. In this limit, transport can be described by Landauer-Büttiker theory [38]. Ref.…”

Section: Quantum Feedback Networkmentioning

confidence: 99%

Feedback Control in Quantum Transport

Emary

2016

Understanding Complex Systems

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Abstract. Quantum transport is the study of the motion of electrons through nano-scale structures small enough that quantum effects are important. In this contribution I review recent theoretical proposals to use the techniques of quantum feedback control to manipulate the properties of electron flows and states in quantum-transport devices. Quantum control strategies can be grouped into two broad classes: measurement-based control and coherent control, and both are covered here. I discuss how measurement-based techniques are capable of producing a range of effects, such as noise suppression, stabilisation of nonequillibrium quantum states and the realisation of a nano-electronic Maxwell's demon. I also describe recent results on coherent transport control and its relation to quantum networks. IntroductionFeedback control of quantum mechanical systems is a rapidly emerging topic [1,2], developed most fully in the field of quantum optics [3]. Only recently have these ideas been extended to quantum transport, a field which looks to understand and control the motion of electrons through structures on the nano-scale [4]. The aim of this contribution is to review these recent developments.Broadly speaking, quantum feedback strategies may usefully be classified into two types:• Measurement-based control, where the quantum system is subject to measurements, the classical information from which forms the basis of the feedback loop; • Coherent control, where the system, the controller and their interconnections are phase coherent such that the information flow in the feedback loop is of quantum information [5].Mirroring the situation in optics, most of the work to-date on feedback in quantum transport has been within the measurement-based paradigm. In Sec. 1.2 here, we discuss a number of different measurement-based schemes

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Shot noise in mesoscopic conductors

Cited by 2,516 publications

References 300 publications

A cold-atom Fermi–Hubbard antiferromagnet

A cold-atom Fermi–Hubbard antiferromagnet

Shot noise measurements in graphene

Feedback Control in Quantum Transport

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