Quantized conductance at the Majorana phase transition in a disordered superconducting wire

Area of Science:

• Condensed Matter Physics
• Topological Quantum Matter
• Superconductivity

Background:

• Superconducting wires lacking time-reversal and spin-rotation symmetries can host topological phases.
• These topological phases support Majorana bound states, crucial for topological quantum computing.
• Direct detection of Majorana bound states is challenging due to low-lying excitations in disordered wires.

Purpose of the Study:

• To identify robust signatures of topological phase transitions in superconducting wires.
• To overcome the limitations posed by disorder and low-lying excitations for Majorana bound state detection.
• To establish a reliable method for probing topological properties in superconducting systems.

Main Methods:

• Theoretical analysis of superconducting wires in a topological phase.
• Investigation of quantized thermal conductance and electrical shot noise power at the phase transition.
• Examination of magnetoconductance oscillations in a ring geometry.
• Utilizing the determinant of the reflection matrix as a topological quantum number.

Main Results:

• The topological phase transition is unequivocally signaled by quantized thermal conductance and electrical shot noise power.
• These quantized signatures are independent of the degree of disorder in the wire.
• In a ring geometry, the phase transition is marked by a period doubling of magnetoconductance oscillations.

Conclusions:

• Quantized thermal conductance and electrical shot noise serve as direct, disorder-independent probes of topological phase transitions.
• Period doubling in magnetoconductance oscillations provides a distinct signature in ring geometries.
• The sign of the determinant of the reflection matrix acts as a topological quantum number, unifying these signatures.