13,842 research outputs found
Quantum Memristors
Technology based on memristors, resistors with memory whose resistance
depends on the history of the crossing charges, has lately enhanced the
classical paradigm of computation with neuromorphic architectures. However, in
contrast to the known quantized models of passive circuit elements, such as
inductors, capacitors or resistors, the design and realization of a quantum
memristor is still missing. Here, we introduce the concept of a quantum
memristor as a quantum dissipative device, whose decoherence mechanism is
controlled by a continuous-measurement feedback scheme, which accounts for the
memory. Indeed, we provide numerical simulations showing that memory effects
actually persist in the quantum regime. Our quantization method, specifically
designed for superconducting circuits, may be extended to other quantum
platforms, allowing for memristor-type constructions in different quantum
technologies. The proposed quantum memristor is then a building block for
neuromorphic quantum computation and quantum simulations of non-Markovian
systems
Coulomb Oscillations in Antidots in the Integer and Fractional Quantum Hall Regimes
We report measurements of resistance oscillations in micron-scale antidots in
both the integer and fractional quantum Hall regimes. In the integer regime, we
conclude that oscillations are of the Coulomb type from the scaling of magnetic
field period with the number of edges bound to the antidot. Based on both
gate-voltage and field periods, we find at filling factor {\nu} = 2 a tunneling
charge of e and two charged edges. Generalizing this picture to the fractional
regime, we find (again, based on field and gate-voltage periods) at {\nu} = 2/3
a tunneling charge of (2/3)e and a single charged edge.Comment: related papers at http://marcuslab.harvard.ed
Bilayer Quantum Hall Systems at nuT = 1: Coulomb Drag and the Transition from Weak to Strong Interlayer Coupling
Measurements revealing anomalously large frictional drag at the transition between the weakly and strongly coupled regimes of a bilayer two-dimensional electron system at total Landau level filling factor nuT = 1 are reported. This result suggests the existence of fluctuations, either static or dynamic, near the phase boundary separating the quantized Hall state at small layer separations from the compressible state at larger separations. Interestingly, the anomalies in drag seem to persist to larger layer separations than does interlayer phase coherence as detected in tunneling
Double layer two-dimensional electron systems: Probing the transition from weak to strong coupling with Coulomb drag
Frictional drag measurements revealing anomalously large dissipation at the
transition between the weakly- and strongly-coupled regimes of a bilayer
two-dimensional electron system at total Landau level filling factor
are reported. This result suggests the existence of fluctuations, either static
or dynamic, near the phase boundary separating the quantized Hall state at
small layer separations from the compressible state at larger separations.
Interestingly, the anomalies in drag seem to persist to larger layer
separations than does interlayer phase coherence as detected in tunneling.Comment: 4 pages, 4 figure
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