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What Is Nonlocal in Counterfactual Quantum Communication?
Yakir Aharonov1, Daniel Rohrlich2
1School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, and Department of Physics, Chapman University, Orange, California 92866, USA.
Physical Review Letters
|January 15, 2021
Summary
Researchers demonstrate that a conserved current of modular angular momentum (Lz mod 2ℏ) can transmit one bit of quantum information without particle exchange. This finding clarifies counterfactual quantum communication mechanisms.
Area of Science:
- Quantum Communication
- Quantum Information Theory
- Fundamental Physics
Background:
- The concept of counterfactual quantum communication proposes information transfer without physical particle exchange.
- Previous work suggested modular angular momentum currents could carry information.
Purpose of the Study:
- To investigate and confirm the mechanism of information transfer in counterfactual quantum communication.
- To identify the specific physical quantity responsible for transmitting one bit of information.
Main Methods:
- Analysis of a locally conserved, massless current: modular angular momentum (Lz mod 2ℏ).
- Integration of the flux of this current between observers.
- Comparison of the integrated flux with the eigenvalues of Lz mod 2ℏ.
Main Results:
- The flux of the Lz mod 2ℏ current precisely accounts for the one bit of information transferred.
- The integrated flux equals one of the two eigenvalues (0 or ℏ), confirming information transmission.
- This result was achieved without employing weak values, differing from prior methods.
Conclusions:
- A conserved current of modular angular momentum (Lz mod 2ℏ) is definitively shown to carry one bit of quantum information.
- This provides a clear physical explanation for counterfactual quantum communication.
- The findings reinforce the understanding of quantum information transfer mechanisms.
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