Controlling a quantum point junction on the surface of an antiferromagnetic topological insulator

1. An electronic device, comprising:

an A-type antiferromagnetic topological insulator (AFM TI) having a surface and comprising a bulk domain wall structure supporting a 1D chiral channel between two adjacent surface layer regions that support an anomalous Hall effect of opposite sign;

a step structure formed on the surface of the AFM TI and intersecting the bulk domain wall structure, the surface step structure supporting 1D chiral channels between surface layer and adjacent second layer regions that support an anomalous Hall effect of opposite sign;

the intersection of the bulk domain wall structure and the surface step structure providing thereat a quantum point junction (QPJ).

2. The electronic device of claim 1 , wherein the antiferromagnetic topological insulator is made of candidate materials comprising any of MnBi 2 Te 4 , MnBi 4 Te 7 , EuIn 2 As 2 , and NpBi.

3. The electronic device of claim 1 , wherein a wave-packet (WP) entering the electronic device along a domain wall structure channel is split into two component WPs by the QPJ, the two component WPs traveling away from the QPJ along step structure channels.

4. The electronic device of claim 1 , wherein propagation of wave-packets (WPs) by the QPJ is characterized by an S-matrix associated with the QPJ, wherein manipulation of the QPJ using magnetic and electrostatic scanning tunneling microscopy (STM) tips in proximity with the QPJ changes the S-matrix characterization of the QPJ.

5. The electronic device of claim 1 , wherein a plurality of quantum point junctions are provided, and the electronic device comprises an electron interferometer.

6. The electronic device of claim 1 , wherein a plurality of quantum point junctions are provided, and the electronic device comprises a local magnetic sensor.

7. The electronic device of claim 1 , wherein a plurality of controllable quantum point junctions are provided, and the electronic device is used to manipulate qubits in a quantum computing system.

8. The electronic device of claim 7 , wherein the controllable quantum point junctions comprise quantum gates organized to perform quantum computations.

9. A method of forming an electronic device, comprising:

on a surface of an A-type antiferromagnetic topological insulator (AFM TI) comprising a bulk domain wall structure supporting a 1D chiral channel between two adjacent surface layer regions that support an anomalous Hall effect of opposite sign, forming a surface step structure intersecting the bulk domain wall structure, the surface step structure supporting 1D chiral channels between surface layer and adjacent second layer regions that support an anomalous Hall effect of opposite sign;

the intersection of the bulk domain wall structure and the surface step structure providing thereat a quantum point junction (QPJ).

10. The method of claim 9 , wherein the antiferromagnetic topological insulator is made of candidate materials comprising any of MnBi 2 Te 4 , MnBi 4 Te 7 , EuIn 2 As 2 , and NpBi.

11. The method of claim 9 , wherein a wave-packet (WP) entering the electronic device along a domain wall structure channel is split into two component WPs by the QPJ, the two component WPs traveling away from the QPJ along step structure channels.

12. The method of claim 9 , wherein propagation of wave-packets (WPs) by the QPJ of the electronic device is characterized by an S-matrix associated with the QPJ, the method further comprising manipulation of the QPJ using magnetic and electrostatic scanning tunneling microscopy (STM) tips in proximity with the QPJ changes the S-matrix characterization of the QPJ.

13. The method of claim 9 , wherein a plurality of quantum point junctions are provided, and the electronic device comprises an electron interferometer.

14. The method of claim 9 , wherein a plurality of controllable quantum point junctions are provided, and the electronic device is used to manipulate qubits in a quantum computing system.

15. The electronic device of claim 7 , wherein the controllable quantum point junctions comprise quantum gates organized to perform quantum computations.

16. A Mach-Zehnder electron interferometer implemented on a surface of an A-type antiferromagnetic topological insulator (AFM TI), the surface having a bulk domain wall structure supporting a 1D chiral channel between two adjacent surface layer regions that support an anomalous Hall effect of opposite sign;

a step structure formed on the surface of the AFM TI and intersecting the bulk domain wall structure, the surface step structure supporting 1D chiral channels between surface layer and adjacent second layer regions that support an anomalous Hall effect of opposite sign;

the intersection of the bulk domain wall structure and the surface step structure providing thereat a quantum point junction (QPJ).

17. The interferometer of claim 16 , wherein the antiferromagnetic topological insulator is made of candidate materials comprising any of MnBi 2 Te 4 , MnBi 4 Te 7 , EuIn 2 As 2 , and NpBi.

18. The interferometer of claim 16 , wherein a wave-packet (WP) entering the electronic device along a domain wall structure channel is split into two component WPs by the QPJ, the two component WPs traveling away from the QPJ along step structure channels.

19. The interferometer of claim 16 , wherein propagation of wave-packets (WPs) by the QPJ is characterized by an S-matrix associated with the QPJ, wherein manipulation of the QPJ using magnetic and electrostatic scanning tunneling microscopy (STM) tips in proximity with the QPJ changes the S-matrix characterization of the QPJ.

20. The interferometer of claim 16 , wherein:

a plurality of controllable quantum point junctions are provided, and the interferometer is used to manipulate qubits in a quantum computing system; and

the controllable quantum point junctions comprise quantum gates organized to perform quantum computations.