Manipulation Zone for Qubits in Quantum Dots

Abstract

An electronic component is formed by a semiconductor component or a semiconductor-like structure having gate electrode assemblies for manipulating the quantum state of qubits in quantum dots. It comprises a substrate comprising a two-dimensional electron gas or electron hole gas. Electrical contacts connect the gate electrode assemblies to voltage sources. A first gate electrode assembly having gate electrodes is arranged on a surface of the electronic component to generate movable potential wells in the substrate. A second gate electrode assembly serves to generate a potential barrier, which is adjacent to the first gate electrode assembly. The gate electrode assemblies have parallel electrode fingers, whereby the electrode fingers of the first gate electrode assembly are periodically and alternately interconnected in order to effect an almost continuous movement of the potential wells through the substrate.

Claims

1.-14. (canceled)

15. An electronic component (10), which is formed by a semiconductor component or a semiconductor-like structure having gate electrode assemblies (16, 18, 40) for manipulating a quantum state of qubits in quantum dots (52, 54), comprising: a substrate (12) with a two-dimensional electron gas or electron hole gas; electrical contacts for connecting the gate electrode assemblies (16, 18, 40) to voltage sources; a first gate electrode assembly (16) having gate electrodes (20, 22, 24, 26), which is arranged on a surface (14) of the electronic component (10), for producing a potential wells (56, 58) in the substrate (12); a second gate electrode assembly (40) for generating a potential barrier, which is adjacent to the first gate electrode assembly (16); parallel electrode fingers (28,30, 32,34) being part of the gate electrode assemblies (16, 18, 40), the electrode fingers (28, 30, 32, 34) of the first gate electrode assembly (16) being periodically and alternately interconnected, which effects an almost continuous movement of the potential wells (56, 58) through the substrate (12); and a manipulator (39) that sets the qubit to a definable quantum state in a manipulation zone (38), wherein the manipulation zone (38) is provided in an adjacent region (36), which is formed by the first and second gate electrode assembly (16, 40).

16. The electronic component (10) according to claim 15, further comprising means for a switchable magnetic field for splitting electronic states with respect to their quantum mechanical states in the quantum dots (52, 54).

17. The electronic component (10) according to claim 15, wherein the manipulator (39) comprises means for generating an oscillating magnetic field and/or a gradient magnetic field in the manipulation zone (38).

18. The electronic component (10) according to claim 15, wherein the manipulator (39) comprises a microwave generator, which radiates microwaves into the manipulation zone (38) to manipulate the quantum state of the quantum dot (52, 54).

19. The electronic component (10) according to claim 15, wherein the manipulator (39) comprises a third gate electrode assembly (18) with gate electrodes (22, 24) for transporting a quantum dot (52) by a potential well (56), which is arranged adjacent to a surface (14) of the electronic component (10) and to the manipulation zone (38).

20. The electronic component (10) according to claim 19, wherein the third gate electrode assembly (18) in the region adjacent to the manipulation zone (38) has a fourth gate electrode assembly.

21. The electronic component (10) according to claim 15, wherein the first and third gate electrode assembly (16, 18) each comprise two parallel gate electrodes, which form a channel-like structure.

22. The electronic component (10) according to claim 15, wherein the substrate (12) of the electronic component (10) comprises gallium arsenide (GaAs) and/or silicon germanium (SiGe).

23. The electronic component (10) according to claim 15, wherein the respectively interconnected gate electrodes (20, 22, 24, 26) are configured such that a periodic and/or phase-shifted voltage can be applied to them.

24. The electronic component (10) according to claim 15, wherein every third electrode finger (28, 30, 32, 34) is connected to a gate electrode (20, 22, 24, 26).

25. The electronic component (10) according to claim 15, further comprising means for connecting one and/or two qubits of a quantum computer.

26. A method for the electronic component (10) according to claim 15, wherein the quantum dot (52) or the quantum dots (52, 54) can be moved into and out of the manipulation zone (38) by the first or third gate electrode assembly (16, 18), respectively.

27. A method for the electronic component (10) according to claim 23, wherein the quantum dot (52) or the quantum dots (52, 54) are moved into the manipulation zone (38) for an exchange interaction.

28. A method for the electronic component (10) according to claim 23, wherein the quantum dot (52, 54) within a magnetic gradient field is moved back and forth to manipulate a qubit in the manipulation zone (38).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 shows a schematic top view of a section of an exemplary embodiment of an electronic component with a gate arrangement for manipulating the quantum state of a quantum dot or a charge carrier.

[0041] FIG. 2 shows a schematic diagram of the sequence of manipulation in the manipulation zone of a variant with gate electrode assemblies provided on both sides for two movable potential wells for single qubit operations.

[0042] FIG. 3 shows a schematic diagram of the sequence of manipulation in the manipulation zone of a variant with gate electrode assemblies provided on one side for one movable potential well for single qubit operations.

[0043] FIG. 4 shows a schematic diagram of the sequence of manipulation in the manipulation zone of a variant for two-qubit operations.

DETAILED DESCRIPTION

[0044] FIG. 1 shows a first exemplary embodiment of an electronic component 10, which is formed from a semiconductor heterostructure. The structures of the component are preferably nanoscale structures. Undoped silicon germanium (SiGe) is used as the substrate 12 for the electronic component 10. The electronic component 10 is designed in such a manner that it comprises a two-dimensional electron gas (2DEG). Gate electrode assemblies 16, 18 are provided on a surface 14 of the substrate 12.

[0045] The gate electrode assemblies 16, 18 each have two gate electrodes 20, 22, 24, 26. The individual gate electrodes are electrically isolated from one another in a suitable manner with insulating layers 27. The gate electrode assemblies 16, 18, 40 are provided in layers, and one insulating layer 27 is provided between each gate electrode 20, 22, 24, 26 of the gate electrode assemblies 16, 18, 40. The gate electrodes 20, 22, 24, 26 further comprise electrode fingers 28, 30, 32, 34, which are arranged parallel to another on the surface 14 of the substrate 12.

[0046] In an adjacent region 36 where the gate electrode assemblies 16, 18 adjoin, a manipulation zone 38 is formed. A manipulator 39, which contains a further gate electrode assembly 40, is located in the manipulation zone 38. The gate electrode assembly 40 comprises gate electrodes 42, 44, 46, which form at least one static potential well. The gate electrode assembly 40 further comprises pump gate electrodes 48, 50, each of which can set a quantum dot or a charge carrier in motion or in oscillation.

[0047] The gate electrode assemblies 16, 18, 40 are supplied with a suitable voltage via electrical connections. By suitably applying sinusoidal voltages to the gate electrodes 20, 22, 24, 26 of the gate electrode assemblies 16, 18, a potential well is generated in the substrate 12. A quantum dot or charge carrier trapped in this potential well can thus be transported through the substrate. The potential well is transported longitudinally through the substrate through suitable control of the electrode fingers 28, 30, 32, 34 with sinusoidal voltages. The quantum dot or charge carrier confined in such a potential well can be transported with this potential well over a greater distance in the two-dimensional electron gas of the substrate 12 made of SiGe without experiencing a quantum mechanical change of state.

[0048] FIG. 2 shows a schematic diagram of the sequence of manipulation of a quantum dot or charge carrier 52, 54 in the manipulation zone 38 for a single qubit operation. The diagram shows a section of the electronic component 10 so that only the electrode fingers 28, 30, 32, 34; the barrier gate electrodes 42, 44, 46; and the pump gate electrodes 48, 50 are visible in the section. Sequences from A to F of the positions of the potential wells 56, 58, 60 in the substrate 12 are shown below this to explain the function. The electrode fingers 28, 30, 32, 34 of the gate electrode assemblies 16, 18 form the movable potential wells 56, 58 through the substrate 12. The movement of the potential wells 56, 58 is effected by appropriately interconnecting the electrode fingers 28, 30, 32, 34. The electrode fingers 28, 30, 32, 34 of the gate electrode assembly 16, 18 provided for this purpose are periodically and alternately interconnected, which effects an almost continuous movement of the potential wells 56, 58 through the substrate 12.

[0049] A static double well 60 is formed in the manipulation zone 38. The static double well 60 is produced by the barrier gate electrodes 42, 44, 46. First, a quantum dot 54 is brought with the movable potential well 58 into the static double potential well 60 in the manipulation zone 38. The quantum dot 54 can assume a defined quantum mechanical state by the manipulator 39, for example a gradient magnetic field. Another quantum dot 52 waits outside the manipulation zone 38. A defined quantum state of the quantum dot 54 is achieved through movement in the magnetic field gradient of the manipulator 39. It is now the possible to have the quantum dot 54 assume a defined quantum state through delocalization in the double well (E) or through rapid back and forth motions in the magnetic field gradient (F). The quantum dots 52, 54 brought out of the manipulation zone 38 assume defined quantum mechanical states in this manner.

[0050] FIG. 3 shows a schematic diagram of the sequence of manipulation of a quantum dot or charge carrier 54 in the manipulation zone 38 for a single qubit operation. The diagram shows a section of the electronic component 10 so that only the electrode fingers 32, 34; the barrier gate electrodes 42, 44, 46; and the pump gate electrodes 48, 50 are visible in the section. Sequences from A to F of the positions of the potential wells 58, 60 in the substrate 12 are shown below this to explain the function. The electrode fingers 32, 34 of the gate electrode assembly 18 form the movable potential well 58 through the substrate 12. The movement of the potential well 58 is effected by appropriately interconnecting the electrode fingers 32, 34. The electrode fingers 32, 34 of the gate electrode assembly 18 provided for this purpose are periodically and alternately interconnected, which effects an almost continuous movement of the potential well 58 through the substrate 12.

[0051] The static double well 60 is formed in the manipulation zone 38. The static double well 60 is produced by the barrier gate electrodes 42, 44, 46. The quantum dot 54 is brought with the movable potential well 58 into the static double potential well 60 in the manipulation zone 38. The quantum dot 54 can assume a defined quantum mechanical state by the manipulator 39, for example a gradient magnetic field. A defined quantum state of the quantum dot 54 is achieved through movement in the magnetic field gradient of the manipulator 39. It is now the possible to have the quantum dot 54 assume a defined quantum state through delocalization in the double well (E) or through rapid back and forth motions in the magnetic field gradient. The quantum dot 54 brought out of the manipulation zone 38 assumes a defined quantum mechanical state in this manner.

[0052] FIG. 4 shows a schematic diagram of the sequence of manipulation in the manipulation zone 38 of a further variant for two-qubit operations. The diagram shows a section of the electronic component 10 so that only the electrode fingers 28, 30, 32, 34; the barrier gate electrodes 42, 44, 46; and the pump gate electrodes 48, 50 are visible in the section. Sequences from A to E of the positions of the potential wells 56, 58, 60 in the substrate 12 are shown below this to explain the function. The electrode fingers 28, 30, 32, 34 of the gate electrode assemblies 16, 18 form the potential wells 56, 58, which can be moved through the substrate 12. The movement of the potential wells 56, 58 is effected by appropriately interconnecting the electrode fingers 28, 30, 32, 34. The electrode fingers 28, 30, 32, 34 of the gate electrode assembly 16, 18 provided for this purpose are periodically and alternately interconnected, which effects an almost continuous movement of the potential wells 56, 58 through the substrate 12.

[0053] The static double well 60 is formed in the manipulation zone 38. The static double well 60 is produced in this case as well by the barrier gate electrodes 42, 44, 46. The quantum dots 52, 54 are transported with the movable potential wells 56, 58 to the static double potential well 60 in the manipulation zone 38 and are each brought into the double potential well 60. The quantum dots 52, 54 can assume a defined quantum mechanical state by the manipulator 39, for example a gradient magnetic field. Via exchange interaction 64, two-qubit operations can be carried out between the quantum dots 52, 54. The quantum dots 52, 54 brought out of the manipulation zone 38 assume defined quantum mechanical states in this manner.

LIST OF REFERENCE SIGNS

[0054] 10 Electronic component [0055] 12 Substrate [0056] 14 Surface [0057] 16 Gate electrode assembly [0058] 18 Gate electrode assembly [0059] 20 Gate electrode [0060] 22 Gate electrode [0061] 24 Gate electrode [0062] 26 Gate electrode [0063] 27 Insulating layer [0064] 28 Electrode fingers [0065] 30 Electrode fingers [0066] 32 Electrode fingers [0067] 34 Electrode fingers [0068] 36 Adjacent region [0069] 38 Manipulation zone [0070] 39 Manipulator [0071] 40 Gate electrode assembly [0072] 42 Barrier gate electrodes [0073] 44 Barrier gate electrodes [0074] 46 Barrier gate electrodes [0075] 48 Pump gate electrodes [0076] 50 Pump gate electrodes [0077] 52 Quantum dot [0078] 54 Quantum dot [0079] 56 Movable potential well [0080] 58 Movable potential well [0081] 60 Static double well [0082] 62 Horizontal arrows [0083] 64 Horizontal double arrow