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Information Gain and Loss for a Quantum Maxwell's Demon
M Naghiloo1, J J Alonso2, A Romito3
1Department of Physics, Washington University, St. Louis, Missouri 63130, USA.
Physical Review Letters
|August 8, 2018
Summary
Researchers experimentally studied a quantum Maxwell
Area of Science:
- Quantum Information Science
- Quantum Thermodynamics
- Superconducting Circuits
Background:
- The Maxwell's demon paradox explores the relationship between information and thermodynamics.
- Quantum systems introduce unique challenges and possibilities for information processing and energy conversion.
- Superconducting qubits offer a controllable platform for studying fundamental quantum phenomena.
Purpose of the Study:
- To experimentally investigate the information dynamics of a quantum Maxwell's demon using a superconducting qubit.
- To explore the conversion of information into work via quantum coherent feedback.
- To verify quantum fluctuation theorems in the presence of feedback and imperfect measurements.
Main Methods:
- Utilized continuous weak measurements on a driven superconducting qubit.
- Employed quantum coherent feedback to process information gained from measurements.
- Analyzed single quantum trajectories to verify theoretical predictions.
Main Results:
- Demonstrated the conversion of information into work using quantum feedback on a superconducting qubit.
- Verified a quantum fluctuation theorem by analyzing information from single quantum trajectories.
- Showed that quantum backaction in imperfect measurements can lead to information loss.
Conclusions:
- Experimental evidence supports the thermodynamic cost of information in quantum systems.
- Quantum feedback provides a mechanism to extract work from information, consistent with fluctuation theorems.
- The study highlights the role of measurement backaction and initial state purity in quantum information dynamics.
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