The ‘quantum critical’ physics that develops in the vicinity of quantum phase transitions is believed to underpin the behaviors of many strongly correlated electronic systems, such as heavy fermions, high temperature superconductors, and emerging exotic quasiparticles. However, the microscopic complexity of these materials impedes their quantitative understanding, and conductance measurements often do not permit the unambiguous observation of different quasiparticles.
Tunable circuits could circumvent these obstacles. With a device implementing the equivalent of an analogue quantum simulator for the so-called three-channel ‘charge’ Kondo model [1], we explored the strongly correlated physics in a parameter space including two dissimilar regimes of quantum criticality [2]. At the two-channel fixed point, we show that by exploiting Maxwell’s relations the predicted presence of a free Majorana particle (zero mode) could be revealed from its fractional entropy kBln(2)/2 [3].
References:
[1] K. Matveev, Sov. Phys. JETP 72, 892 (1991); K. Matveev, Phys. Rev. B 51, 1743 (1995).
[2] Z. Iftikhar et al., Nature 526, 233 (2015); Z. Iftikhar et al., Science 360, 1315 (2018).
[3] C. Han et al., arXiv:2108.12878 (2021).
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