Graphene quantum Hall effect parallel resistance arrays

Abstract

As first recognized in 2010, epitaxial graphene on SiC(0001) provides a platform for quantized Hall resistance (QHR) metrology unmatched by other two-dimensional structures and materials. Here we report graphene parallel QHR arrays, with metrologically precise quantization near 1000 Ω. These arrays have tunable carrier densities, due to uniform epitaxial growth and chemical functionalization, allowing quantization at the robust ν = 2 filling factor in array devices at relative precision better than 10 −8 . Broad tunability of the carrier density also enables investigation of the ν = 6 plateau. Optimized networks of QHR devices described in this work suppress Ohmic contact resistance error using branched contacts and avoid crossover leakage with interconnections that are superconducting for quantizing magnetic fields up to 13.5 T. Our work enables more direct scaling of resistance for quantized values in arrays of arbitrary network geometry.

Anomalous universal conductance as a hallmark of non-locality in a Majorana-hosted superconducting island

“…This high precision, fortunately, has been reported in e.g., ref. 65 when measuring the conductance quanta. In the low-conductance limit, this requirement on the measurement precision is also achieved in e.g., refs.…”

Design of an enhanced mechanism for a new Kibble balance directly traceable to the quantum SI

“…Among the advantages offered by graphene-based QHR standards is their ability to maintain the fully quantized state at higher currents and temperature. NIST researchers fabricated thirteen single element graphene QHR standards in parallel and operate at the Landau level i = 2 plateau, giving a nominal value of R K /26 ≈ 992.8 [10]. Even though the graphene QHR array in Panna et al show experiments with maximum currents up to 0.3 mA, measurements have already been published showing single Hall bar graphene devices maintaining quantization for currents up to 0.7 mA [11].…”

“…Since a QHR has been designed for this purpose [10], we put the focus on the redesign and optimization of the Kibble balance. Each individual subsystem of the Kibble balance is being investigated regarding new opportunities for improvement.…”

“…The force over displacement curve of the final stage of the mechanism was monitored and compared to the analytical model. The rotational stiffness in equation (10) can be transferred to a linear stiffness at the guiding mechanism in vertical direction by dividing equation (10) by the square of the balance lever arm l 2 1 . Furthermore, ϕ ≈ z/l 1 .…”

Conception of an enhanced mechanism for a new Kibble balance directly traceable to the quantum SI

“…Among the advantages offered by graphene-based QHR standards is their ability to maintain the fully quantized state at higher currents and temperature. NIST researchers fabricated thirteen single element graphene QHR standards in parallel and operate at the Landau level i = 2 plateau, giving a nominal value of R K /26 ≈ 992.8 Ω [10]. Even though the graphene QHR array in Panna et al show experiments with maximum currents up to 0.3 mA, measurements have already been published showing single Hall bar graphene devices maintaining quantization for currents up to 0.7 mA [11].…”