Method and Device for Detecting Very Small Capacitance Variations

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This invention relates to a method and device for detecting extremely small changes in capacitance (as little as 10 or 100 attofarads) by using oscillating circuits to generate reference and oscillator signals. Minute changes in capacitance, such as those caused by the spin state of an electron in a quantum dot (used in quantum computing), produce a phase shift in the oscillator signal. This phase shift is detected with a phase detector (e.g., in a type 2 phase-locked loop), allowing reliable read-out of quantum information from quantum bits (qubits) in quantum computers.

Use CasesContent extracted from patent full text and abstract with AI.

• Quantum computers: Reading the spin state of electrons in quantum dots (qubits) for quantum information processing.
• Nano-electronics: High-precision capacitance sensing in semiconductor and nanostructure devices.
• Research: Studying fundamental electron properties and spin states in experimental physics.
• Sensor technology: Developing ultrasensitive capacitive sensors for detection of minute physical or chemical changes.
• Scientific instrumentation: Implementing in advanced laboratory equipment for precise electrical characterization.

BenefitsContent extracted from patent full text and abstract with AI.

• Enables detection of extremely small capacitance variations, down to attofarad levels, increasing sensitivity by orders of magnitude.
• Allows for reliable and simplified read-out of qubit (quantum bit) states in quantum computing technology.
• Facilitates high-precision measurements in nano-scale devices and experimental setups.
• Reduces complexity and technical requirements for measuring quantum states, making implementation easier.
• Supports the development of new, high-performance sensors and instruments for cutting-edge applications.

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Patent Abstract

The invention relates to a method for determining a capacitance change, wherein an oscillating reference signal (R) and an oscillating oscillator signal (O) are generated by electrical resonant circuits, wherein a capacitance change of less than 100 attofarads or less than 10 attofarads changes the phase of the oscillator signal (O), and following the change in phase of the oscillator signal (O), the resulting phase shift between the reference signal (R) and the oscillator signal (O) is determined by a phase detector (PD). The invention further relates to a device for carrying out a method comprising a phase-locked loop of type 2, including an electrical resonant circuit for generating an oscillator signal (O), with a quantum dot, with a quasi-zero-dimensional semiconductor structure adjacent to the quantum dot, with an electrical connection or coupling between the quasi-zero-dimensional semiconductor structure and the resonant circuit. By means of the invention, the spin state of an electron in a quantum computer can be reliably read out using simple technical means.