Majorana fermions are zero-energy quasiparticles that may exist in superconducting vortices and interfaces, but their detection is problematic since they have no charge. This is an obstacle to the realization of topological quantum computation, which relies on Majorana fermions to store qubits in a way which is insensitive to decoherence. We show how a pair of neutral Majorana fermions can be converted reversibly into a charged Dirac fermion. These two types of fermions are predicted to exist on the metallic surface of a topological insulator (such as Bi2Se3). Our Dirac-Majorana fermion converter enables electrical detection of a qubit by an interferometric measurement.
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http://dx.doi.org/10.1103/PhysRevLett.102.216404 | DOI Listing |
Phys Rev Lett
December 2024
Beijing Computational Science Research Center, Beijing 100193, China.
In hybrid systems where nanowires are proximity-coupled with superconductors, the low-energy theory fails to determine the topological phase with Majorana fermion (MF) when the magnetic field or proximity coupling is much stronger. To overcome this limitation, we propose a holistic approach that defines MF by considering both the motion of electrons in the nanowire and the quasiparticle excitations in the superconductor. This approach transcends the constraints of low-energy theory and offers broad applicability.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom.
Quasiparticles are low-energy excitations with important roles in condensed matter physics. An intriguing example is provided by Majorana quasiparticles, which are equivalent to their antiparticles. Despite being implicated in neutrino oscillations and topological superconductivity, their experimental realizations remain very rare.
View Article and Find Full Text PDFACS Nano
December 2024
School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
Realizing Majorana Fermions has always been regarded as a crucial and formidable task in topological superconductors. In this work, we report a physical mechanism and a material platform for realizing Majorana zero modes (MZMs). This material platform consists of open circular helix molecule (CHM) proximity coupled with an -wave superconductor (under an external magnetic field) or interconnected-CHM chain coupled with a phase-bias -wave superconducting heterostructure (without any external magnetic field).
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
In the presence of an external magnetic field, the Kitaev model could host either gapped topological anyons or gapless Majorana fermions. In α-RuCl_{3}, the gapped and gapless cases are only separated by a 30° rotation of the in-plane magnetic field vector. The presence or absence of the spectral gap is key for understanding the thermal transport behavior in α-RuCl_{3}.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Department of Physics, Indian institute of technology, Kanpur, India.
We theoretically study the transport signatures of unpaired Floquet Majorana fermions in the Josephson current of weakly linked, periodically driven topological superconductors. We obtain analytical expressions for the occupation of the Floquet Majorana fermions in the presence of weak coupling to thermal reservoirs, and show that, similar to undriven topological superconductors, for sufficiently low temperatures and large systems the Josephson current involving Floquet Majorana fermions is 4π-periodic in the phase difference across the junction and depends linearly on the coupling between superconductors. Moreover, unlike the static case, the amplitude of the Josephson current can be tuned by setting the unbiased chemical potential of the driven superconductors at multiple harmonics of the drive frequency.
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