> Find a quantum money scheme which uses only four possible single-qubit states but is better than Wiesner’s scheme (i.e. the scheme which uses the four states {|ψ1 =|0 , |ψ2 =|1 , |ψ3 =|+ , |ψ4 =|−}), in the sense that the optimal attack has success probability <3/4.
One doesn't come to mind, sorry. My sense, not being a real expert in this, is that the various public-key quantum money proposals don't have a lot to tie them together conceptually. This perhaps makes it hard to write a good survey of the space.
I like this problem (source: http://users.cms.caltech.edu/~vidick/teaching/120_qcrypto/HW1.pdf (see for hint))
> Find a quantum money scheme which uses only four possible single-qubit states but is better than Wiesner’s scheme (i.e. the scheme which uses the four states {|ψ1 =|0 , |ψ2 =|1 , |ψ3 =|+ , |ψ4 =|−}), in the sense that the optimal attack has success probability <3/4.
This is neat! I would stumble across quantum money papers on the arXiv once in a while, but never followed up. Do you have a favorite overview?
One doesn't come to mind, sorry. My sense, not being a real expert in this, is that the various public-key quantum money proposals don't have a lot to tie them together conceptually. This perhaps makes it hard to write a good survey of the space.