Majorana Zero Mode Experimental Signature Protocol

Answer

The standard protocol for identifying Majorana zero modes (MZMs) in semiconductor nanowire devices is tunneling spectroscopy: differential conductance (dI/dV) measurements in a normal-superconductor (N-S) junction at ultra-low temperatures (~20 mK) in a dilution refrigerator, with bias voltage applied across the junction and conductance recorded as a function of bias voltage, magnetic field, and gate voltages bf227f5a. The target signature is a zero-bias conductance peak quantized at 2e^2/h 8ebadd7b, a prediction grounded in resonant Andreev reflection theory b1de830d; however, the 2e^2/h value is a target limit, not proof by itself, because trivial Andreev states can also produce such peaks b27e2a89.

Summary

The corpus is unanimous on the measurement protocol: differential conductance tunneling spectroscopy of an N-S junction at ultra-low temperatures (~20 mK) in a dilution refrigerator, sweeping bias voltage and recording dI/dV as a function of bias voltage, magnetic field, and gate voltages bf227f5a``1b0cbd45``9eeeb693. The targeted signature is a zero-bias conductance peak at 2e^2/h 8ebadd7b``b55329f8``b1de830d, but the corpus also documents that this peak is not unique to MZMs: partially separated Andreev bound states (ps-ABSs) can produce zero-bias conductance plateaus quantized at the same value ec717aaa``b27e2a89. The disagreement is over interpretation: a 2e^2/h zero-bias peak is a predicted signature, but not proof by itself, of a topological Majorana mode.

Evidence

• Law, Lee, and Ng (Physical Review Letters, 2009) — theoretical prediction that Majorana fermions induce resonant Andreev reflection, producing a linear tunneling conductance of 2e^2/h at zero bias when an odd number of channels is involved. b1de830d
• Pan et al. (Physical Review B, 2021) — systematic investigation of zero-bias conductance peaks in Majorana nanowires, comparing topological Majorana bound states and quasi-Majorana bound states. 8ebadd7b
• Chen et al. (Physical Review Letters, 2019) — tunneling measurements on InSb nanowire/superconductor hybrid devices; zero-bias conductance peaks resembling Majorana bound states become common at finite magnetic fields. b55329f8
• Moore et al. (Physical Review B, 2018) — showed that partially separated Andreev bound states (ps-ABSs) in quantum dot-semiconductor-superconductor heterostructures produce robust zero-bias conductance plateaus quantized at 2e^2/h. ec717aaa
• PRB 98.155314 (2018) — describes the N-S junction tunneling spectroscopy protocol: dI/dV measurements at ~20 mK in a dilution refrigerator, recording conductance as a function of bias voltage, magnetic field, and gate voltages. bf227f5a
• PRL 129.167702 (2022) — describes the same protocol (dI/dV, N-S junction, ~20 mK, dilution refrigerator; conductance vs bias voltage, magnetic field, gate voltages) as the key signature of an MZM. 1b0cbd45
• PRL 129.167702 (2022) — duplicate record, identical protocol description. 9eeeb693
• Communications Physics (2023) — the standard test is differential tunnelling conductance vs bias voltage; a Majorana zero mode should produce a zero-bias peak, with ideal single-channel quantized signature 2e^2/h; this is a target limit, not proof by itself, because trivial Andreev states can also produce peaks. b27e2a89

Methodology

I grouped the eight records by role: (1) protocol descriptions, (2) theoretical predictions of the 2e^2/h signature, (3) experimental/theoretical demonstrations of the same signature in trivial (non-topological) systems. The protocol descriptions agree with each other, so I merged their features rather than presenting them as separate findings. I did not pool quantitative claims—all concern the same target value (2e^2/h), so no rounding or conversion was needed; the raw figures are given exactly as in the source. The key comparison was between Majorana-attributable peaks and trivial-state peaks at the same conductance value, which I preserved as a contrast rather than resolving. I treated the duplicate protocol record (9eeeb693) as redundant, not as independent corroboration.

Limitations

• The corpus cannot settle whether a given zero-bias conductance peak at 2e^2/h originates from a topological Majorana zero mode or from a trivial Andreev bound state, because both are predicted to produce the same signature.
• The records are truncated; several claims end mid-sentence, so the full logic of the Pan et al. distinction between topological Majorana bound states and quasi-Majorana bound states is not available here.
• The number of channels in the measured junctions, which determines whether 2e^2/h is the correct quantized value, is not stated in most records.