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Related Concept Videos

Time-Domain Interpretation of PD Control01:07

Time-Domain Interpretation of PD Control

66
Proportional-Derivative (PD) control is a widely used control method in various engineering systems to enhance stability and performance. In a system with only proportional control, common issues include high maximum overshoot and oscillation, observed in both the error signal and its rate of change. This behavior can be divided into three distinct phases: initial overshoot, subsequent undershoot, and gradual stabilization.
Consider the example of control of motor torque. Initially, a positive...
66
Open and closed-loop control systems01:17

Open and closed-loop control systems

562
Control systems are foundational elements in automation and engineering. They are broadly categorized into open-loop and closed-loop systems. These classifications hinge on the presence or absence of feedback mechanisms, significantly influencing the system's performance, complexity, and application.
An open-loop control system operates without feedback from the output. It consists of two primary elements: the controller and the controlled process. The controller receives an input signal...
562
Control System Problem01:21

Control System Problem

91
In an open-loop system, such as a basic thermostat, the poles of the transfer function influence the system's response but do not determine its stability. However, when feedback is introduced to form a closed-loop system, such as an advanced thermostat that adjusts heating based on room temperature, stability is governed by the new poles of the closed-loop transfer function.
When forming a closed-loop system, issues can arise if the poles cross into the unstable region, leading to potential...
91
Feedback control systems01:26

Feedback control systems

252
Feedback control systems are categorized in various ways based on their design, analysis, and signal types.
Linear feedback systems are theoretical models that simplify analysis and design. These systems operate under the principle that their output is directly proportional to their input within certain ranges. For instance, an amplifier in a control system behaves linearly as long as the input signal remains within a specific range. However, most physical systems exhibit inherent nonlinearity...
252
Frequency-Domain Interpretation of PD Control01:24

Frequency-Domain Interpretation of PD Control

74
Proportional-Derivative (PD) controllers are widely used in fan control systems to improve stability and performance. A fan control system can be effectively represented using a Bode plot to illustrate the impact of a PD controller through its transfer function. The Bode plot visually conveys how PD control modifies the fan's response across various frequencies, providing a frequency domain interpretation of the controller's behavior.
The proportional control gain, combined with the...
74
BIBO stability of continuous and discrete -time systems01:24

BIBO stability of continuous and discrete -time systems

293
System stability is a fundamental concept in signal processing, often assessed using convolution. For a system to be considered bounded-input bounded-output (BIBO) stable, any bounded input signal must produce a bounded output signal. A bounded input signal is one where the modulus does not exceed a certain constant at any point in time.
To determine the BIBO stability, the convolution integral is utilized when a bounded continuous-time input is applied to a Linear Time-Invariant (LTI) system....
293
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  11. Beating The Ramsey Limit On Sensing With Deterministic Qubit Control.
  1. Home
  3. Research Domains
  5. Engineering
  7. Communications Engineering
  9. Signal Processing
  11. Beating The Ramsey Limit On Sensing With Deterministic Qubit Control.

Related Experiment Video

Gradient Echo Quantum Memory in Warm Atomic Vapor
10:00

Gradient Echo Quantum Memory in Warm Atomic Vapor

Published on: November 11, 2013

12.7K

Beating the Ramsey limit on sensing with deterministic qubit control.

M O Hecht1,2, Kumar Saurav1,3, Evangelos Vlachos1,2

  • 1Center for Quantum Information Science and Technology, University of Southern California, Los Angeles, CA, 90089, USA.

Nature Communications
|April 29, 2025

View abstract on PubMed

Summary
This summary is machine-generated.

We developed a new qubit measurement protocol that enhances sensitivity by stabilizing the Bloch vector. This method improves qubit frequency measurement accuracy despite decoherence, offering practical benefits for quantum technologies.

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Related Experiment Videos

Gradient Echo Quantum Memory in Warm Atomic Vapor
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Published on: November 11, 2013

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Generation and Coherent Control of Pulsed Quantum Frequency Combs
06:42

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Area of Science:

  • Quantum Information Science
  • Quantum Sensing
  • Superconducting Circuits

Background:

  • Qubit frequency shifts are crucial for sensing environmental variables.
  • Ramsey interference is a standard method for detecting these shifts.
  • Decoherence limits the sensitivity of traditional Ramsey measurements.

Purpose of the Study:

  • To introduce a novel protocol for enhancing qubit frequency measurement sensitivity.
  • To overcome the limitations imposed by decoherence in quantum sensing.
  • To improve the precision of measurements in quantum computing and sensor applications.

Main Methods:

  • Applying a continuous drive to stabilize a component of the qubit's Bloch vector.
  • Implementing the protocol on a superconducting qubit.
  • Theoretical analysis of the protocol's performance and robustness.

    • Main Results:

    • Demonstrated a 1.65x enhancement in sensitivity per measurement shot on a superconducting qubit.
    • Achieved a 1.09x enhancement in sensitivity per qubit evolution time compared to Ramsey interferometry.
    • Theoretical analysis predicted unconditional enhancements and robustness to miscalibrations.

    Conclusions:

    • The new protocol significantly enhances qubit frequency measurement sensitivity in the presence of decoherence.
    • It offers practical advantages, requiring no feedback or extra resources.
    • The protocol is readily applicable to diverse quantum computing and quantum sensor technologies.