Quantum spin hall-based charging energy-protected quantum computation
This application concerns quantum computing, and in particular to structures and mechanisms for providing topologically protected quantum computation. In certain embodiments, a magnetic tunnel barrier is controlled that separates Majorona zero modes (“MZMs”) from an edge area (e.g., a gapless edge) of a quantum spin hall system. In particular implementations, the magnetic tunnel barrier is formed from a pair of magnetic insulators whose magnetization is held constant, and the magnetic tunnel barrier is tuned by controlling a gate controlling the electron density around the magnetic insulator in the QSH plane, thereby forming a quantum dot. And, in some implementations, a state of the quantum dot is read out (e.g., using a charge sensor as disclosed herein).
1. A method of operating quantum device comprising:
controlling a magnetic tunnel barrier that separates Majorona zero modes (“MZMs”) from a gapless edge of a quantum spin hall system,
wherein the magnetic tunnel barrier is formed from a magnetic insulator whose magnetization is held constant, and
wherein the magnetic tunnel barrier is tuned by controlling a gate controlling the electron density around the magnetic insulator in the QSH plane, thereby forming a quantum dot.
2. The method of claim 1 , further comprising reading out a state of the quantum dot.
3. The method of claim 1 , wherein the quantum spin hall system implements a tetron qubit.
4. The method of claim 3 , wherein the tetron qubit does not comprise a Josephson junction.
5. The method of claim 3 , wherein the tunable quantum dot is further located between or substantially between two magnetic insulators.
6. The method of claim 5 , wherein the two magnetic insulators are non-tunable.
7. The method of claim 1 , wherein the quantum spin hall system implements a hexon qubit.
8. The method of claim 7 , wherein the tetron qubit does not comprise a Josephson junction.
9. The method of claim 7 , wherein the tunable quantum dot is further located between or substantially between two magnetic insulators.
10. The method of claim 7 , wherein the two magnetic insulators are non-tunable.
11. A tetron qubit, comprising three pairs of Majorana zero modes, wherein the tetron qubit further comprises a tunable quantum dot configured to control a magnetic tunnel barrier between two neighboring Majorana zero modes.
12. The tetron qubit of claim 11 , wherein the tetron qubit does not comprise a Josephson junction.
13. The tetron qubit of claim 11 , wherein the tunable quantum dot is further located between or substantially between two magnetic insulators.
14. The tetron qubit of claim 13 , wherein the two magnetic insulators are non-tunable.
15. The tetron qubit of claim 11 , wherein the tetron qubit is part of a topologically protected quantum computing system.
16. A hexon qubit comprising four pairs of Majorana zero modes, wherein the hexon qubit further comprises a tunable quantum dot configured to control a magnetic tunnel barrier between two neighboring Majorana zero modes.
17. The hexon qubit of claim 16 , wherein the hexon qubit does not comprise a Josephson junction.
18. The hexon qubit of claim 16 , wherein the tunable quantum dot is further located between or substantially between two magnetic insulators.
19. The hexon qubit of claim 18 , wherein the two magnetic insulators are non-tunable.
20. The hexon qubit of claim 16 , wherein the hexon qubit is part of a topologically protected quantum computing system.