Articolo in rivista, 2020, ENG, 10.1103/PhysRevApplied.14.024059

Cascaded Quantum Hall Bisection and Applications to Quantum Metrology

Momtaz, Zahra Sadre; Heun, Stefan; Biasiol, Giorgio; Roddaro, Stefano

CNR; Scuola Normale Super Pisa; IOM CNR; Univ Pisa

We demonstrate a programmable quantum Hall circuit that implements an iterative voltage bisection scheme and allows any binary fraction (k/2(n)) of the fundamental resistance quantum R-K/2 = h/2e(2) to be obtained. The circuit requires a number n of bisection stages that only scales logarithmically with the resolution of the set of possible output fractions. The value of k can be set to any integer between 1 and 2(n) by proper and easily predictable gate configuration. The architecture exploits gate-controlled routing, mixing, and equilibration of edge modes of robust quantum Hall states. The device does not contain internal Ohmic contacts and is thus naturally robust towards stray-resistance effects. Our scheme offers an alternative way to obtain custom quantum Hall resistance standards, and its potential advantages are discussed. The basic viability of the approach is demonstrated in a proof-of-principle two-stage bisection circuit built on a high-mobility GaAs/(Al, Ga)As heterostructure operating at a temperature of 260 mK and a magnetic field of 4.1 T. Our prototype achieves a relative quantization precision of the order of 10(-4), which is limited by the experimental setup rather than by the circuit itself.

Physical Review Applied 14 (2)

Keywords

quantum Hall, Quantum Metrology

CNR authors

Roddaro Stefano, Biasiol Giorgio, Heun Stefan

CNR institutes

IOM – Istituto officina dei materiali, NANO – Istituto Nanoscienze