Electro-optical circuit for performing topological quantum computation
A quantum processing device having a type II superconducting medium is provided. Majorana-carrying vortices may be created at some of the defects in the medium by a magnetic flux source. Once created, one or more vortices may be depinned from its departure location, dragged through the medium and repined at a destination location, respectively. One or more laser beams may be respectively used for moving the vortices. The power of the laser beams may be independently controlled. The vortices may be moved for readout and/or for computation, as needed, such as for providing quantum computational gates.
1. A quantum processing device comprising:
a type II superconducting medium comprising a plurality of defects;
a magnetic flux source configured to produce, during operation of the quantum processing device, a magnetic flux that induces, within the type II superconducting medium, vortices pinned at locations of some of the defects, such that the vortices are separated from each other based on a vortex distribution, wherein two or more vortices are used to enact quantum computational gates of the quantum processing device;
a laser source configured to provide two or more laser beams with controllable power; and
a beam-steering module configured to
redirect the two or more laser beams to departure locations of two or more vortices while the two or more laser beams are provided with a first power that causes unpinning of the two or more vortices from the departure locations, respectively, and allows the two or more laser beams to drag the unpinned vortices through the type II superconducting medium,
sweep the two or more laser beams along respective paths from the departure locations to destination locations of the two or more vortices, and
redirect the two or more laser beams to the destination locations while the two or more laser beams are provided with a second power smaller than the first power that causes pinning of the dragged vortices.
2. The quantum processing device of claim 1 , wherein the magnetic flux source comprises at least one wire and corresponding current source, wherein a magnitude of the magnetic flux is controllable based on a target number of vortices and the vortex distribution.
3. The quantum processing device of claim 1 , wherein the magnetic flux source comprises a plurality of wires and corresponding current sources, each current source is independently controllable, wherein the plurality of wires is positioned with respect to the type II superconducting medium to produce an asymmetric magnetic flux within the type II superconducting medium.
4. The quantum processing device of claim 1 , further comprising material positioned over the type II superconducting medium and a device configured to determine a position and number of the vortices within the type II superconducting medium and transfer the position and number to a processor.
5. The quantum processing device of claim 1 , wherein the beam-steering module is configured to enact one or more quantum computational gates by braiding two or more vortices.
6. The quantum processing device of claim 5 , wherein the beam-steering module is configured to:
redirect a first laser beam to a first location of a first vortex and a second laser beam to a second location of a second vortex while the first and second laser beams are provided with the first power,
sweep the first laser beam along a first path from the first location to the second location and the second laser beam along a second path from the second location to the first location, and
redirect the first laser beam to the second location and the second laser beam to the first location while the first and second laser beams are provided with the second power.
7. The quantum processing device of claim 5 , wherein the beam-steering module is configured to:
redirect a laser beam to a location of a first vortex, sweep a power of the laser beam to depin the first vortex,
sweep the laser beam along a loop-shaped path from the location of the first vortex encircling a second vortex a single time and back to the location of the first vortex and ramping the power down to repin the first vortex.
8. The quantum processing device of claim 5 , further comprising a processor configured to instruct the beam-steering module to enact the one or more quantum computational gates based on a computation.
9. The quantum processing device of claim 1 , wherein the laser source comprises a laser and a plurality of beam splitters to provide the two or more laser beams.
10. The quantum processing device of claim 1 , wherein the beam-steering module is configured to move the two or more laser beams at speeds of in a range of 0.5-5.0 cm/s.
11. The quantum processing device of claim 1 , wherein each vortex has a spin orbit of about 0.1 μm in diameter and wherein the two or more lasers beams have a beam width of about 1 μm in diameter.
12. The quantum processing device of claim 1 , wherein the vortex distribution is such that adjacent vortices are separated by about 1 μm to about 100 μm.
13. The quantum processing device of claim 1 , wherein the type II superconducting medium is a superconducting film disposed on a substrate.
14. The quantum processing device of claim 13 , wherein the magnetic flux source comprises at least one wire, wherein the at least one wire is disposed on the substrate.
15. The quantum processing device of claim 13 , wherein the superconducting film comprises mixtures of Fe with one or more heavy elements.
16. The quantum processing device of claim 15 , wherein
the mixtures of Fe with one or more heavy elements comprise Fe(Te,Se), and
the substrate comprises SrTiO 3 .
17. The quantum processing device of claim 15 , wherein
the superconducting film comprises Cu—Bi 2 Se 3 , and
the substrate comprises InP.
18. The quantum processing device of claim 14 , wherein
the superconducting film comprises BiPd, and
the substrate comprises Al 2 O 3 .
19. The quantum processing device of claim 1 , wherein the type II superconducting medium is part of a NbSe 2 /Bi 2 Se 3 heterostructure.
20. The quantum processing device of claim 1 , wherein the beam-steering module is further configured to redirect two laser beams to departure locations of two vortices while the two laser beams are provided with the first power that causes unpinning of the vortices from the departure-locations, respectively, and allows the two laser beams to drag the unpinned vortices through the type II superconducting medium toward a readout module and each other to cause fusing of the two vortices for readout and return the two vortices to respective departure locations after readout, where the two vortices comprise a first vortex carrying a first Majorana-zero-mode (MZM) and a second vortex carrying a second MZM, the first vortex moving over a first path and the second vortex moving over a second path, the first path and the second path running parallel to each other over a readout location.
21. The quantum processing device of claim 20 , further comprising a readout module, the readout module comprising a Coulomb-blockade based quantum dot sensor, wherein when the first vortex and the second vortex are adjacent to the quantum dot, a tunnel junction is formed and the readout module detects whether a pair of the first MZM and the second MZM are in a vacuum state or a charged state.
22. A quantum processing device comprising:
a type II superconducting medium comprising a plurality of defects;
a magnetic flux source configured to produce, during operation of the quantum processing device, a magnetic flux that induces, within the type II superconducting medium, vortices pinned at locations of some of the defects, such that the vortices are separated from each other based on a vortex distribution, wherein two or more vortices are used to enact quantum computational gates of the quantum processing device;
a laser source configured to provide a laser beam with controllable power; and
a beam-steering module configured to
redirect the laser beam to a departure location of a vortex while the laser beam is provided with a first power that causes unpinning of the vortex from the departure location,
sweep the laser beam along a path from the departure location to a destination location, and
redirect the laser beam to the destination location while lowering the power from the first power to a second power to cause pinning of the vortex.
23. The quantum processing device of claim 22 , wherein the departure location is the same as the destination location.
24. The quantum processing device of claim 23 , wherein the path comprises encircling another vortex a single time.