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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20190421T180951Z
LAST-MODIFIED:20181030T193950Z
DTSTART:20181128T200000Z
DTEND:20181128T210000Z
UID:event2043@bu.edu
URL:http://physics.bu.edu/events/show/2043
SUMMARY:Andreev or Majorana\, Cooper finds out
DESCRIPTION:Featuring Constantin Schrade\, MIT\nHosted by: Claudio Chamon\n
\nPart of the Biophysics/Condensed Matter Seminar Series.\n\nTopological su
perconductors hosting spatially separated Majorana bound states form a key
component of robust quantum computing architectures. In candidate platforms
for topological superconductors\, such as semiconducting-superconducting h
ybrid nanowires\, the emergence of a zero-bias conductance peak has been pe
rceived as a first step towards verifying the existence of Majorana bound s
tates. However\, zero-bias conductance peak measurements have difficulties
in differentiating zero-energy Majorana bound states from zero-energy Andre
ev bound states that can also appear in topological superconductor candidat
e systems. Hence\, we need a more refined diagnostic tool to differentiate
Majorana bound states from Andreev bound states.\nIn this talk\, I will add
ress this issue by revisiting a well-established superconducting circuit el
ement: The Cooper pair transistor; realizable by a superconducting island i
n contact to superconducting leads. For a trivial island\, the critical sup
ercurrent between the leads exhibits a well-known 2e-periodicity in the isl
and-gate charge. In contrast\, I will show that for an island with spatiall
y separated zero-energy Majorana or Andreev bound states the periodicity of
the magnitude of the critical supercurrent transitions to 1e in the island
-gate charge. Moreover\, I will argue that for Andreev bound states the cur
rent-phase relation displays a sign reversal when the parity of the charge
ground state of the island changes between even and odd. Notably\, I will d
emonstrate that for Majorana bound states the same sign reversal does not o
ccur.\nFinally\, I will put these results into the context of Majorana qubi
ts. More specifically\, I will discuss a Majorana-based qubit in an all-sup
erconducting circuit\, a "Majorana Superconducting Qubit". I will demonstra
te how universal quantum computation can be achieved in such a device and d
iscuss advantages over conventional superconducting qubits.\n\n [1] C. Schr
ade and L. Fu\, Andreev or Majorana\, Cooper finds out\,arXiv:1809.06370\n
[2] C. Schrade and L. Fu\, Majorana Superconducting Qubit\, arXiv:1803.0100
2\n [3] C. Schrade and L. Fu\, Parity-controlled 2Pi Josephson effect media
ted by Majorana Kramers pairs\, Phys. Rev. Lett. 120\, 267002 (2018)
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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