Semiconductor Nuclear Spin Qudits With Electric Field Control
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Solution Overview
Problem
Existing quantum computing technologies face challenges in integrating multiple qubits due to the large size of transmons, short-range interactions in electron spins, and scalability issues with ion traps, limiting the integration and control of quantum processing elements.
Innovation Solution
A method and apparatus utilizing nuclear spin qudits encoded in semiconductor materials with dopant atoms, manipulated via electric fields to generate electric field gradients, enabling quantum information encoding and control without magnetic resonance, suitable for integration with conventional electronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmons are used for quantum computing, then fast and high-fidelity operations are achieved, but the large size prevents integration of hundreds or thousands of qubits on a single chip
Solution Approach 1:
The patent changes the physical parameter of the quantum processing element from macroscopic transmon circuits to atomic-scale dopant atoms in semiconductor. This parameter change reduces the area from millimeter-scale to nanometer-scale, enabling integration of thousands of qubits while maintaining quantum coherence through the atomic structure's inherent stability.
Solution Approach 2:
The patent uses identical dopant atoms (e.g., phosphorus in silicon) as standardized quantum processing elements, replacing the complex transmon circuit design with a simple, repeatable atomic structure. This copying approach allows mass production and integration of many identical qubits using existing semiconductor fabrication techniques.
2Duration of action of stationary object
If electron spins in semiconductors are used, then long coherence times are achieved, but the short-range exchange coupling interaction poses challenges for integrating control lines in tight spacing
Solution Approach 1:
The patent replaces the mechanical/electromagnetic control system (control lines and exchange coupling) with a purely electric field-based control mechanism. Electric fields can penetrate the semiconductor and directly manipulate the nuclear spin states without requiring physical control lines between closely spaced qubits, thus simplifying the control architecture.
Solution Approach 2:
The patent introduces electric field gradients as an intermediary mechanism to control nuclear spins. Instead of direct electron spin-electron spin interaction requiring tight spacing and complex control lines, the electric field gradient acts as a mediator that can address individual nuclear spins through their quadrupole moments, enabling control at larger spacings.
3Reliability
If ions are trapped in vacuum, then exceptionally long coherence times and high gate fidelities are achieved, but the manufacturability of trapping systems with large numbers of ions remains unclear and many lasers are needed
Solution Approach 1:
The patent changes the environment parameter from high-vacuum ion traps to solid-state semiconductor hosts, and the control method from laser-based to electric field-based. This allows integration with existing semiconductor manufacturing infrastructure while achieving the desired quantum processing performance.
Solution Approach 2:
The patent makes the semiconductor substrate serve multiple functions: it provides the physical host for dopant atoms, maintains them at fixed positions through the crystal lattice, provides the electric field control mechanism, and enables integration with conventional electronic devices. This multi-functionality eliminates the need for separate vacuum chambers, laser systems, and positioning mechanisms required by ion trap approaches.
4Reliability
If nuclear spin qudits are manipulated via magnetic resonance, then quantum information can be encoded, but the requirement for magnetic fields and magnetic resonance complicates integration with conventional electronic devices
Solution Approach 1:
The patent replaces magnetic field-based manipulation with electric field-based manipulation. By exploiting the electric quadrupole moment of nuclear spins with I>1/2, the system uses electric field gradients to encode and manipulate quantum information, eliminating magnets and magnetic resonance equipment while enabling direct integration with conventional electronic control circuits.
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
Enables efficient integration and control of quantum processing elements using electric fields, allowing for scalable quantum computing and strain sensing in cryogenic environments.
Implementation Method 1
applying a magnetic field to the dopant atom to separate the energies of the spin states associated with the nucleus of the dopant atom
Implementation Method 2
The voltage applied to the conductive electrode contributes to generating an electric field gradient at the dopant atom. The electric field gradient is partially due to the applied field and partially due to the morphology of the semiconductor crystal in proximity of the dopant atom. The electric field gradient allows to modify the energy of the nuclear spin states.
Implementation Method 3
applying a second electric signal to the at least one conductive electrode so that an oscillating electric field gradient is generated at the nucleus of the dopant atom to induce transitions between the quantum mechanical states of the nuclear spin
Data Source
AI summary
The present disclosure is directed a quantum processing element comprising: a semiconductor and a dielectric material forming an interface with the semiconductor; a dopant atom with nuclear spin of quantum number larger than ½ embedded in the semiconductor at a distance from the interface, at least one conductive electrode disposed in a manner such that there is at least a portion of dielectric material between the at least one conductive electrode and the dopant atom. The disclosure is also directed to a method of operating the quantum processing element comprising the steps of: applying a magnetic field to the dopant atom to separate the energies of the spin states associated with the nucleus of the dopant atom; applying a voltage to the at least one conductive electrode to generate an electric field gradient at a nucleus of the dopant atom; and encoding quantum information in the nuclear spin of the nucleus via the applied voltage.