arXiv subjects

Dmitri V. Averin

Publications and source records attributed to Dmitri V. Averin.

At least 37 records · Page 2Linked to original sources

arXiv2010

Splitting electrons into quasiparticles with fractional edge-state Mach-Zehnder interferometer

We have studied theoretically the tunneling between two edges of Quantum Hall liquids (QHL) of different filling factors, $ν_{0,1}=1/(2 m_{0,1}+1)$, with $m_0 \geq m_1\geq 0$, through two separate point contacts in the geometry of Mach-Zehnder interferometer [Y. Ji et al., Nature {\bf 422}, 415 (2003); I. Neder et al., Phys.\ Rev.\ Lett. {\bf 96}, 016804 (2006)]. The quasi-particle formulation of the interferometer model is derived as a dual to the initial electron model, in the limit of strong electron tunneling reached at large voltages or temperatures. For $m\equiv 1+m_{0}+m_{1}>1$, the tunneling of quasiparticles of fractional charge $e/m$ leads to non-trivial $m$-state dynamics of effective flux through the interferometer, which restores the regular "electron" periodicity of the current in flux despite the fractional charge and statistics of quasiparticles. The exact solution available for equal times of propagation between the contacts along the two edges demonstrates that the interference pattern of modulation of the tunneling current by flux depends on voltage and temperature only through a common amplitude.

cond-mat.str-el↗

arXiv2010

Charge transfer statistics in symmetric fractional edge-state Mach-Zehnder interferometer

We have studied the zero-temperature statistics of charge transfer between the two edges of Quantum Hall liquids with filling factors $ν_{0,1}=1/(2 m_{0,1}+1)$ forming Mach-Zehnder interferometer. The known Bethe ansatz solution for symmetric interferometer is used to obtain the cumulant-generating function of charge at constant voltage $V$ between the edges. Its low-$V$ behavior can be interpreted in terms of electron tunneling, while its large-$V$ asymptotics reproduces the $m$-state dynamics ($m\equiv 1+m_{0}+m_{1}$) of quasiparticles with fractional (for $m>1$) charge and statistics. We also analyze the transition region between electrons and quasiparticles.

cond-mat.str-el↗

arXiv2010

Violation of the fluctuation-dissipation theorem in time-dependent mesoscopic heat transport

We have analyzed the spectral density of fluctuations of the energy flux through a mesoscopic constriction between two equilibrium reservoirs. It is shown that at finite frequencies, the fluctuating energy flux is not related to the thermal conductance of the constriction by the standard fluctuation-dissipation theorem, but contains additional noise. The main physical consequence of this extra noise is that the fluctuations do not vanish at zero temperature together with the vanishing thermal conductance.

cond-mat.mes-hall↗

arXiv2009

One-Dimensional Impenetrable Anyons in Thermal Equilibrium. IV. Large Time and Distance Asymptotic Behavior of the Correlation Functions

This work presents the derivation of the large time and distance asymptotic behavior of the field-field correlation functions of impenetrable one-dimensional anyons at finite temperature. In the appropriate limits of the statistics parameter, we recover the well-known results for impenetrable bosons and free fermions. In the low-temperature (usually expected to be the "conformal") limit, and for all values of the statistics parameter away from the bosonic point, the leading term in the correlator does not agree with the prediction of the conformal field theory, and is determined by the singularity of the density of the single-particle states at the bottom of the single-particle energy spectrum.

cond-mat.stat-mech↗

arXiv2009

Tunneling without tunneling: wavefunction reduction in a mesoscopic qubit

The transformation cycle and associated inequality are suggested for the basic demonstration of the wavefunction reduction in a mesoscopic qubit in measurements with quantum-limited detectors. Violation of the inequality would show directly that the qubit state changes in a way dictated by the probabilistic nature of the wavefunction and inconsistent with the dynamics of the Schrödinger equation: the qubit tunnels through an infinitely large barrier. Estimates show that the transformation cycle is within the reach of current experiments with superconducting qubits.

cond-mat.mes-hall↗

arXiv2009

Non-conformal asymptotic behavior of the time-dependent field-field correlators of 1D anyons

The exact large time and distance behavior of the field-field correlators has been computed for one-dimensional impenetrable anyons at finite temperatures. The result reproduces known asymptotics for impenetrable bosons and free fermions in the appropriate limits of the statistics parameter. The obtained asymptotic behavior of the correlators is dominated by the singularity in the spectral density of the quasiparticle states at the bottom of the band, and differs from the predictions of the conformal field theory. One can argue, however, that the anyonic response to the low-energy probes is still determined by the conformal terms in the asymptotic expansion.

cond-mat.stat-mech↗

arXiv2009

One-Dimensional Impenetrable Anyons in Thermal Equilibrium. III. Large distance asymptotics of the space correlations

Using the determinant representation for the field-field correlation functions of impenetrable anyons at finite temperature obtained in a previous paper, we derive a system of nonlinear partial differential equations completely characterizing the correlators. The system is the same as the one for impenetrable bosons but with different initial conditions. The large-distance asymptotic behavior of the correlation functions is obtained from the analysis of the Riemann-Hilbert problem associated with the system of differential equations. We calculate both the exponential and pre-exponential factors in the asymptotics of the field-field correlators. The asymptotics derived in this way agree with those of the free fermions and impenetrable bosons in the appropriate limits, $κ\to 1$ and $κ\to 0$, of the statistics parameter $κ$, and coincide with the predictions of the conformal field theory at low temperatures.

cond-mat.stat-mech↗

arXiv2009

Quantized current of a hybrid single-electron transistor with superconducting leads and a normal-metal island

We discuss the operation of the superconductor - insulator - normal-metal - insulator - superconductor (SINIS) turnstile. This voltage-biased hybrid single-electron transistor (SET) provides current quantization even with only one radio-frequency (rf) control parameter, namely the gate voltage of the single island. We give an overview of the main error mechanisms of the turnstile and consider its feasibility as a quantum current standard. We also present experimental results of pumping with the SINIS structure which show decreased leakage current compared to earlier measurements with the opposite NISIN structure.

cond-mat.mes-hall↗

arXiv2009

Decoherence in adiabatic quantum computation

We have studied the decoherence properties of adiabatic quantum computation (AQC) in the presence of in general non-Markovian, e.g., low-frequency, noise. The developed description of the incoherent Landau-Zener transitions shows that the global AQC maintains its properties even for decoherence larger than the minimum gap at the anticrossing of the two lowest energy levels. The more efficient local AQC, however, does not improve scaling of the computation time with the number of qubits $n$ as in the decoherence-free case. The scaling improvement requires phase coherence throughout the computation, limiting the computation time and the problem size n.

cond-mat.mes-hall↗

arXiv2008

Large-Distance Asymptotic Behavior of the Correlation Functions of 1D Impenetrable Anyons at Finite Temperatures

The large-distance asymptotic behavior of the field-field correlators has been computed for one-dimensional impenetrable anyons at finite temperatures. The asymptotic behavior agrees with the predictions of conformal field theory at low temperatures and reproduces the known results for impenetrable bosons and free fermions in appropriate limits. We have also obtained an integrable system of partial nonlinear differential equations which completely characterizes the 2-point correlation functions. The system is the same as for bosons but with different initial conditions.

cond-mat.stat-mech↗

arXiv2008

Decoherence in rf SQUID Qubits

We report measurements of coherence times of an rf SQUID qubit using pulsed microwaves and rapid flux pulses. The modified rf SQUID, described by an double-well potential, has independent, in situ, controls for the tilt and barrier height of the potential. The decay of coherent oscillations is dominated by the lifetime of the excited state and low frequency flux noise and is consistent with independent measurement of these quantities obtained by microwave spectroscopy, resonant tunneling between fluxoid wells and decay of the excited state. The oscillation's waveform is compared to analytical results obtained for finite decay rates and detuning and averaged over low frequency flux noise.

cond-mat.supr-con↗

arXiv2008

One-Dimensional Impenetrable Anyons in Thermal Equilibrium. II. Determinant Representation for the Dynamic Correlation Functions

We have obtained a determinant representation for the time- and temperature-dependent field-field correlation function of the impenetrable Lieb-Liniger gas of anyons through direct summation of the form factors. In the static case, the obtained results are shown to be equivalent to those that follow from the anyonic generalization of Lenard's formula.

cond-mat.stat-mech↗

arXiv2008

Macroscopic Resonant Tunneling in the Presence of Low Frequency Noise

We develop a theory of macroscopic resonant tunneling of flux in a double-well potential in the presence of realistic flux noise with significant low-frequency component. The rate of incoherent flux tunneling between the wells exhibits resonant peaks, the shape and position of which reflect qualitative features of the noise, and can thus serve as a diagnostic tool for studying the low-frequency flux noise in SQUID qubits. We show, in particular, that the noise-induced renormalization of the first resonant peak provides direct information on the temperature of the noise source and the strength of its quantum component.

cond-mat.mes-hall↗

arXiv2008

One-Dimensional Impenetrable Anyons in Thermal Equilibrium. I. Anyonic Generalization of Lenard's Formula

We have obtained an expansion of the reduced density matrices (or, equivalently, correlation functions of the fields) of impenetrable one-dimensional anyons in terms of the reduced density matrices of fermions using the mapping between anyon and fermion wavefunctions. This is the generalization to anyonic statistics of the result obtained by A. Lenard for bosons. In the case of impenetrable but otherwise free anyons with statistical parameter $κ$, the anyonic reduced density matrices in the grand canonical ensemble is expressed as Fredholm minors of the integral operator ($1-γ\hat θ_T$) with complex statistics-dependent coefficient $γ=(1+e^{\pm iπκ})/ π$. For $κ=0$ we recover the bosonic case of Lenard $γ=2/π$. Due to nonconservation of parity, the anyonic field correlators $\la \fad(x')\fa(x)\ra$ are different depending on the sign of $x'-x$.

cond-mat.stat-mech↗

arXiv2008

Correlation Functions of One-Dimensional Lieb-Liniger Anyons

We have investigated the properties of a model of 1D anyons interacting through a $δ$-function repulsive potential. The structure of the quasi-periodic boundary conditions for the anyonic field operators and the many-anyon wavefunctions is clarified. The spectrum of the low-lying excitations including the particle-hole excitations is calculated for periodic and twisted boundary conditions. Using the ideas of the conformal field theory we obtain the large-distance asymptotics of the density and field correlation function at the critical temperature T=0 and at small finite temperatures. Our expression for the field correlation function extends the results in the literature obtained for harmonic quantum anyonic fluids.

cond-mat.stat-mech↗

arXiv2008

Non-adiabadic charge pumping in a hybrid SET transistor

We study theoretically current quantization in the charge turnstile based on the hybrid (SINIS or NISIN) SET transistor. The quantization accuracy is limited by either Andreev reflection or by Cooper pair - electron cotunneling. The rates of these processes are calculated in the ``above-the-threshold'' regime when they compete directly with the lowest-order tunneling. We show that by shaping the ac gate voltage driving the turnstile, it should be possible to achieve the metrological accuracy of $10^{-8}$, while maintaining the absolute value of the quantized current on the order of 30 pA, just by one turnstile with realistic parameters using aluminium as superconductor.

cond-mat.mes-hall↗

arXiv2007

Coulomb blockade of anyons

Coulomb interaction turns anyonic quasiparticles of a primary quantum Hall liquid with filling factor $ν=1/(2m+1)$ into hard-core anyons. We have developed a model of coherent transport of such quasiparticles in systems of multiple antidots by extending the Wigner-Jordan description of 1D abelian anyons to tunneling problems. We show that the anyonic exchange statistics manifests itself in tunneling conductance even in the {\em absence} of quasiparticle exchanges. In particular, it can be seen as a non-vanishing resonant peak associated with quasiparticle tunneling through a line of three antidots.

cond-mat.mes-hall↗

arXiv2007

Hybrid single-electron transistor as a source of quantized electric current

The basis of synchronous manipulation of individual electrons in solid-state devices was laid by the rise of single-electronics about two decades ago. Ultra-small structures in a low temperature environment form an ideal domain of addressing electrons one by one. A long-standing challenge in this field has been the realization of a source of electric current that is accurately related to the operation frequency $f$. There is an urgent call for a quantum standard of electric current and for the so-called metrological triangle, where voltage from Josephson effect and resistance from quantum Hall effect are tested against current via Ohm's law for a consistency check of the fundamental constants of Nature, $\hbar$ and $e$. Several attempts to create a metrological current source that would comply with the demanding criteria of extreme accuracy, high yield, and implementation with not too many control parameters have been reported. However, no satisfactory solution exists as yet despite many ingenious achievements that have been witnessed over the years. Here we propose and prove the unexpected concept of a hybrid metal-superconductor turnstile in the form of a one-island single-electron transistor with one gate, which demonstrates robust current plateaus at multiple levels of $ef$ within the uncertainty of our current measurement. Our theoretical estimates show that the errors of the present system can be efficiently suppressed by further optimizations of design and proper choice of the device parameters and therefore we expect it to eventually meet the stringent specifications of quantum metrology.

cond-mat.mes-hall↗