Even-denominator fractional quantum Hall state in conventional triple-gated quantum point contact

Abstract

The even-denominator states have attracted considerable attention owing to their possible applications in future quantum technologies. In this letter, we first report a 3/2 diagonal resistance, indicating the existence of a 3/2 state in a nanometer-sized triple-gated quantum point contact (QPC) fabricated on a high-mobility (not ultra-high-mobility) single-layer two-dimensional (2D) GaAs wafer. The center gate plays a crucial role in realizing the QPC’s 3/2 state. Our observation of the 3/2 state using a conventional QPC device, which is a suitable building block for semiconductor quantum devices, paves a new path for the development of semiconductor-based quantum technologies.

Synthesizing $2h/e^2$ resistance plateau at the first Landau level confined in a quantum point contact

“…2(b) at a magnetic field of 7 T. The filling factor 5/3 is supposed to have an edge structure similar to that of the filling factor 2/3, but with an additional outer integer 1 edge mode. Certainly, we observe an intermediate long plateau at (2/3)h/e 2 followed by a short intermediate h/e 2 plateau before the channel pinches off, in line with our previous study using a wider GaAs quantum well and shorter QPC geometry size [19] and in Ref. [18,20].…”

“…By applying a more negative bias to V SG , we can observe a series of quantized conductance steps, similar to the previous report in Ref. [19].…”

“…The QPC is defined by applying a negative bias voltage to a pair of spit gates (V SG ). Additional center metal gate (V CG ) put in between the split gates is used to control the QPC electron density [19], as well as the QPC confinement potential [21][22][23].…”

“…Recently, Fu et al [18] reported a G QPC = (3/2)e 2 /h plateau when the bulk filling is set to ν bulk = 5/3 in an ultra-high mobility constriction and Hayafuchi et al [19] reported a similar plateau in a conventional QPC with a center gate. Yan et al [20] conducted an extended experiment over a wider bulk filling factor and suggested an important role of an elevated density in the constricted region.…”

Anomalous quantized plateaus in two-dimensional electron gas with gate confinement

“…The FQH states with the simplest denominator three provide an example of how the edge structure can be affected in a realistic device. Recently, our group and a group from Tohoku University observed an anomalous even denominator 3=2 À Á Á ðe 2 =hÞ plateau in the 5/3 FQH state in the devices with confined structure 26,27 , and the edge structure accomplished with the 3/2 plateau is of curiosity. It is hard to believe that the edge modes play no role in the formation of such an unexpected quantization.…”