Quantum phase transition detected through one-dimensional ballistic conductance

Abstract

A quantum phase transition is an unequivocal signature of strongly correlated many-body physics. Signatures of such phenomena are yet to be observed in ballistic transport through quantum wires. Recent developments in quantum wires have made it possible to enhance the interaction between the electrons. Here we show that hitherto unexplained anticrossing between conduction energy sub-bands, observed in such experiments, can be explained through a simple yet effective discretised model which undergoes a second order quantum phase transition within the Ising universality class. Accordingly, we observe how the charge distribution, transverse to the direction of the wire will vary across the phase transition. We show that data coming from three different samples with differing electron densities and gate voltages show a remarkable universal scaling behavior, determined by the relevant critical exponent, which is only possible near a quantum phase transition.

Suspended semiconductor nanostructures: physics and technology

“…The formation of double-row configuration was clearly demonstrated in experiments using transverse magnetic electron focusing [40]. It may be noted that quantum wires discussed here were, firstly, not suspended, and, secondly, were formed within the top-gated split gate devices and the transition from single-row to double-row electron transport discussed in references [33][34][35][36][37][38][39]122] refers only to the 1st populated 1D subband.…”

“…In a low-density 1D system when the confinement is sufficiently weak, a line of 1D electrons undergoes a transformation into a zigzag and eventually into a two row situation on further reduction in carrier concentration. Experimentally, a two row situation is manifested by a missing first plateau at 2e 2 /h, and the 4e 2 /h becomes the new ground state, [33][34][35][36][37][38][39]. Also, the zigzag assembly of 1D electrons or the 1D Winger crystal, which happens just before the two rows formation, cannot be measured by the conventional conductance measurements, which was therefore imaged using transverse magnetic focusing technique [40].…”

“…The transition from single-layer to double-layer transport has been observed, for example, in heterostructures with a single wide quantum well [121]. Doublechannel mode has also been implemented in single QPCs [33][34][35][36][37][38][39]122]. The necessary conditions for observing doublerow electron transport are low electron concentration and weak confinement.…”