Communication using quantum entanglement

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Discussion Overview

The discussion centers around the possibility of communication using quantum entanglement, specifically addressing the feasibility of faster-than-light (FTL) communication and the implications of quantum measurement on information transfer. Participants explore theoretical aspects of quantum entanglement, quantum teleportation, and their applications in cryptography.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that FTL communication via quantum entanglement is impossible due to causality violations, questioning if information could be transferred slower than light.
  • Another participant argues that transmitting information via entanglement requires the ability to choose the state of the particle after measurement, which is prohibited by quantum measurement principles.
  • Several participants reference quantum teleportation, noting that classical communication is necessary for its implementation.
  • There is a discussion about the practicality of quantum communication, with one participant stating that since classical information must be sent, it may render quantum communication redundant.
  • Entanglement's role in quantum cryptography is mentioned, highlighting its potential for secure key distribution without the need for physical transport of the key.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and practicality of using quantum entanglement for communication. There is no consensus on whether such communication could be useful or effective.

Contextual Notes

The discussion involves assumptions about the nature of quantum measurement and the requirements for quantum teleportation, which remain unresolved. The implications of classical information transfer in the context of quantum communication are also debated.

phsopher
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As I understand it FTL communication via quantum entanglement would be impossible since it violates causality, but would it be possible to transfer information using QE slower that the speed of light? I recall reading something like that the receiver would not be able to tell whether the transmitter has done anything to his part of the entangled system and thus wouldn't be able to distinguish between the transmitter sending him information and a random measurement. Is this correct? Thanks.
 
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You could only transmit information via entanglement if you could pick which state the particle on your end ends up in after you measure it. But, the nature of quantum measurement forbids this.
 
But you have to communicate information before you can achieve quantum teleportation!
 
kvl said:

But since you have to transfer classical information isn't it rather pointless communication-wise? You could include everything you want to say in the classical bit you're sending anyway.
 
phsopher said:
But since you have to transfer classical information isn't it rather pointless communication-wise? You could include everything you want to say in the classical bit you're sending anyway.

Entanglement is also used in one form of quantum cryptography - Anton Zellinger notes that "In entanglement-based quantum cryptography it leads to the most elegant possible solution of the classic key distribution problem. It implies that the key comes into existence at spatially distant location at the same time and does not need to be transported" http://meetings.aps.org/Meeting/MAR07/Event/63945. Basically Alice and Bob construct a random key from the correlated polarization measurements.

Maybe this is what you had in mind?
 

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