So, I am doing my undergraduate research project in Quantum Cryptography, and I have some confusion in a few areas, especially in the topic of continuous variable quantum key distribution.(adsbygoogle = window.adsbygoogle || []).push({});

From what I understand,

Discrete Variable- Single photon. That is, for example, the BB84 protocol. Bob is measuring 1 photon at a time.

Continuous Variable-Alice encodes key bits (is it more than 1 bit of the key?) in the quadrature X and P.

I understand that is Bob measures in the right quadrature in the BB-84 protocol, then he'll get the right corresponding bit. However, if he chooses the wrong quadrature, he'll get the right bit 50% of the time.

But in CV-QKD, if Bob chooses the right quadrature either X or P, then he'll get the right information, but what happens if he chooses the wrong quadrature?

One more question, in continuous-variable QKD, what is the difference between coherent states and squeeze states. I understand that squeeze states either increase or decrease the certainty in the quadrature X and P because of the uncertainty principle. Is coherent states still used in DV-QKD (similar to weak pulses)?

Thanks for your help!

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# I Understanding Continuous Variable QKD

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