Diamond NV-15N Atomic Clock Using Hyperfine Frequency Locking
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Solution Overview
Problem
Current atomic clocks, particularly Rubidium atomic clocks, suffer from low accuracy and poor long-term stability due to environmental influences and complex lattice environments in solids, limiting their precision and robustness.
Innovation Solution
The implementation of an atomic clock based on the NV-15N coupling spin system in diamond, which utilizes Ramsey interferometry to compare a RF frequency with the 15N hyperfine coupling and feedback to lock the RF frequency, providing a stable frequency standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the zero-field splitting of the NV center is used as a frequency standard, then the atomic clock can be miniaturized and operated at room temperature, but the precision is greatly disturbed by temperature changes
Solution Approach 1:
The patent introduces 15N nuclear spin as an intermediary frequency reference. Instead of directly using the temperature-sensitive NV center zero-field splitting, the system uses the 15N hyperfine coupling frequency (which is less temperature-sensitive) as the reference standard, and compares the RF frequency against this more stable reference through Ramsey interferometry.
Solution Approach 2:
The patent changes the reference frequency parameter from the NV center zero-field splitting (which has large temperature dependence of -74 kHz/K) to the 15N hyperfine coupling frequency (which has much smaller temperature dependence). This parameter substitution resolves the temperature precision problem while maintaining room temperature operation capability.
2Volume of moving object
If Rubidium atomic clocks are used for miniaturization, then the device size and weight are reduced, but the accuracy and long-term stability deteriorate
Solution Approach 1:
The patent creates a composite quantum system combining NV centers in diamond with 15N nuclear spins. This composite system leverages the advantages of both components: the NV center provides long coherence time and easy readout at room temperature, while the 15N nuclear spin provides a stable hyperfine coupling frequency reference, achieving both miniaturization and high precision.
Solution Approach 2:
The patent replaces the traditional Rubidium vapor cell mechanical system with a solid-state diamond NV-15N quantum system. This substitution eliminates the need for bulky vacuum chambers and heating elements, enabling miniaturization while providing better long-term stability through the solid-state environment and nuclear spin reference.
3Reliability
If atomlike defects in solids are used as frequency reference, then the robustness is improved due to stable environment, but the coherence time is shortened by complex lattice environment
Solution Approach 1:
The patent exploits the local quality difference between the NV center environment and the bulk diamond lattice. The NV center is embedded in a locally optimized environment with minimal strain and impurity effects, while the bulk diamond provides the stable solid-state matrix. This local quality optimization maintains long coherence times despite the solid-state environment.
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 results in a highly robust and stable atomic clock with improved long-term stability, capable of achieving precision comparable to commercial atomic clocks, while being less affected by environmental conditions.
Implementation Method 1
There is a method proposed to use a ground-state zero-field splitting of the NV center in diamond as a frequency standard
Implementation Method 2
comparing a RF frequency with a 15N hyperfine coupling through Ramsey interferometry
Implementation Method 3
comparing a RF frequency with a 15N hyperfine coupling through Ramsey interferometry
Implementation Method 4
reading out a difference value between the RF frequency and the 15N hyperfine coupling by collecting a fluorescence signal at NV centers
Data Source
AI summary
A method for implementing an atomic clock based on NV-15N coupling spin system in diamond and a device are provided. The method includes: applying a pulse sequence to jointly initialize NV electron spins and 15N nuclear spins; performing a Ramsey interferometry to compare a RF frequency and a 15N hyperfine coupling; entangling the NV electron spin and the nuclear spin, reading out a state of nuclear spins by collecting a fluorescence signal; calculating a frequency difference between the RF frequency and the 15N hyperfine coupling according to the fluorescence signal, thereby locking the RF frequency to the 15N hyperfine coupling; and outputting the RF frequency as a frequency standard.