Spin Qubit Layout Using Movable Magnetic Domain Walls
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Solution Overview
Problem
Current spin qubit devices face challenges in achieving high integration density and reconfigurability for individual control and manipulation, with limitations in distinguishing qubits and performing logical operations due to the use of permanent magnets and complex cryogenic requirements.
Innovation Solution
The design incorporates a magnet with alternating magnetic domains and domain walls to generate a magnetic field gradient, allowing for distinct resonance frequencies and reconfiguration by moving domain walls with electric current, enabling improved control and integration density of spin qubits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a ferromagnetic magnet is used to produce a magnetic field gradient for individual qubit control, then individual control of qubits is enabled, but the separation distance between qubits must be large which limits integration density
Solution Approach 1:
The magnet is segmented into multiple magnetic domains with alternating magnetization directions arranged along the longitudinal direction. Each domain wall creates a localized magnetic field gradient that can be independently controlled. This segmentation allows multiple qubits to be positioned at different locations along the longitudinal direction, each experiencing a controllable magnetic field gradient from the nearest domain wall, thereby enabling individual control while increasing integration density.
Solution Approach 2:
Different regions of the magnet are assigned different magnetization directions (first and second magnetizations) to create localized magnetic field gradients at specific positions. The magnetic domains are arranged so that domain walls are positioned at locations where qubits are to be placed, creating locally tailored magnetic field gradients for individual qubit control without requiring large separations between qubits.
2Ease of operation
If permanent magnets are used for qubit control, then magnetic field gradient is generated, but the device cannot be reconfigured or reprogrammed
Solution Approach 1:
The magnet is designed with movable domain walls that can be dynamically repositioned along the longitudinal direction by applying current through the first and second electrodes. This dynamic capability allows the magnetic field gradient to be reconfigured in real-time, enabling the device to be reprogrammed for different qubit configurations and logical operations, thus achieving both magnetic field generation and reconfigurability.
Solution Approach 2:
The magnetization configuration of the magnet can be changed by applying current to move domain walls between different positions along the longitudinal direction. This parameter change allows the same physical magnet to produce different magnetic field gradient patterns, enabling reconfiguration of the device for various quantum computing applications without hardware modification.
3Ease of operation
If large separation distance is used between qubits for individual control, then qubit distinguishability is improved, but device size increases
Solution Approach 1:
The magnet is divided into multiple magnetic domains with domain walls positioned at specific intervals along the longitudinal direction. This segmentation creates multiple localized magnetic field gradients within a compact length, allowing qubits to be positioned closer together while maintaining individual distinguishability through the localized gradients from adjacent domain walls.
Solution Approach 2:
Instead of increasing the separation distance along one dimension, the solution utilizes the longitudinal dimension by arranging magnetic domains sequentially along it. The domain walls are positioned at different longitudinal locations, creating magnetic field gradients in the longitudinal direction that provide qubit distinguishability without requiring large transverse separations, thus reducing overall device footprint.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for individual control of spin qubits with increased integration density and reconfigurability, enhancing the ability to perform logical operations and adapt to different configurations without the need for cryogenic environments.
Implementation Method 1
a magnet configured to locally generate a magnetic field gradient between the first and second quantum points, so that the first and second quantum points exhibit first and second resonance frequencies that are different from each other
Implementation Method 2
Under the influence of a magnetic field, two distinct energy levels corresponding to two opposite spin states appear due to the Zeeman effect
Implementation Method 3
The position of the domain walls can be modified by applying a current through the magnet in a direction oriented along its length
Implementation Method 4
It is possible to manipulate the spin state (high and low) of qubits using the technique of electron spin resonance (ESR). By then exposing the qubit to radio frequency (RF) radiation, it is possible to switch the qubit from one spin state to the other
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to an electronic device comprising: - first and second quantum dots (QD1, QD2) arranged along an x-direction, - first and second control grids (41, 42) associated with said quantum dots, - a magnet (20) configured to generate two opposite spin states at each of the first and second quantum dots. Advantageously, the magnet comprises first and second magnetic domains (21, 22) distributed along the x-direction and separated by a domain wall (30). These magnetic domains exhibit first and second magnetizations (A1, A2) of opposite directions along the x-direction. The first and second quantum dots thus perceive first and second magnetic field gradients. The invention also relates to a method for implementing and initializing such a device.