Solid-State Quantum Memory Using NV Center Spin Decoupling
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Solution Overview
Problem
Stable quantum bits capable of storing quantum information for macroscopic time scales and integrating into small portable devices remain a challenging task due to limited coherence times caused by external perturbations and decoherence, especially for single spins or qubits, which are difficult to prepare, address, and measure even at cryogenic temperatures.
Innovation Solution
A system comprising a solid-state lattice with an electronic spin coupled to a nuclear spin, utilizing optical excitation configurations to manage spin coherence, RF and microwave pulse sequences to dynamically decouple spins, and detectors to read nuclear spin states, enabling extended coherence times without cryogenic cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If trapped ions and atoms are used to achieve long coherence times, then coherence time is improved, but device complexity and infrastructure requirements worsen
Solution Approach 1:
The patent extracts the quantum memory function from complex trapped ion/atom systems and implements it in a simplified solid-state lattice using NV centers. By taking out the essential quantum storage capability and removing the need for vacuum chambers, laser cooling apparatus, and complex trapping infrastructure, the system achieves long coherence times with dramatically reduced device complexity and portability.
Solution Approach 2:
The patent changes the physical state parameter from gaseous trapped ions/atoms to solid-state NV centers in diamond lattice. This parameter change enables the system to operate at room temperature without cryogenic cooling, eliminating complex thermal infrastructure while maintaining long nuclear spin coherence times through the isolated solid-state environment.
2Volume of moving object
If single spins are used for quantum operations, then device size is reduced, but measurement and manipulation difficulty increases
Solution Approach 1:
The patent introduces an intermediary optical detection pathway that mediates between the single nuclear spin and the measurement apparatus. By using optically detected magnetic resonance (ODMR) through the NV center's electronic spin, the system enables non-invasive, high-fidelity measurement of the nuclear spin state without requiring direct physical access or complex measurement infrastructure, thus maintaining miniaturization while solving the measurement difficulty.
3Reliability
If electronic spin is coupled to nuclear spin for initialization, then quantum information transfer is improved, but nuclear spin coherence time decreases
Solution Approach 1:
The patent applies periodic radio frequency (RF) pulse sequences to the nuclear spin during storage to dynamically decouple it from the electronic spin. This periodic action temporarily interrupts the hyperfine coupling interaction, preventing coherence transfer back to the electronic spin and suppressing dephasing, thereby extending nuclear spin coherence time while maintaining the ability to initialize and read out quantum information through the electronic spin when needed.
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
Achieves long quantum coherence times at room temperature, allowing for practical quantum devices with nuclear spin coherence times of up to several seconds or minutes, enhancing the stability and fidelity of quantum information storage and processing.
Implementation Method 1
an optical excitation configuration which is arranged to generate first optical radiation to excite the electronic spin to emit output optical radiation
Implementation Method 2
generate second optical radiation of higher power than the first optical radiation to decouple the electronic spin from the nuclear spin thereby increasing coherence time of the nuclear spin
Implementation Method 3
a first pulse source configured to generate radio frequency (RF) excitation pulse sequences to manipulate the nuclear spin and to dynamically decouple the nuclear spin from one or more spin impurities
Implementation Method 4
a second pulse source configured to generate microwave excitation pulse sequences to manipulate the electronic spin causing a change in intensity of the output optical radiation correlated with the electronic spin and with the nuclear spin
Implementation Method 5
a detector configured to detect the output optical radiation correlated with the electronic spin and the nuclear spin so as to detect a nuclear spin state of the nuclear spin
Data Source
AI summary
A system comprising a solid state lattice containing an electronic spin coupled to a nuclear spin; an optical excitation configuration which is arranged to generate first optical radiation to excite the electronic spin to emit output optical radiation without decoupling the electronic and nuclear spins; wherein the optical excitation configuration is further arranged to generate second optical radiation of higher power than the first optical radiation to decouple the electronic spin from the nuclear spin thereby increasing coherence time of the nuclear spin; a first pulse source configured to generate radio frequency (RF) excitation pulse sequences to manipulate the nuclear spin and to dynamically decouple the nuclear spin from one or more spin impurities in the solid state lattice so as to further increase the coherence time of the nuclear spin; a second pulse source configured to generate microwave excitation pulse sequences to manipulate the electronic spin causing a change in intensity of the output optical radiation correlated with the electronic spin and with the nuclear spin via the coupling between the electronic spin and the nuclear spin; and a detector configured to detect the output optical radiation correlated with the electronic spin and the nuclear spin so as to detect a nuclear spin state of the nuclear spin.