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Wiesner Quantum Money: Difference between revisions
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* When Wiesner wrote his thesis, there was no device operating in which the phase coherence of a two-state system was preserved for longer than about a second. | * When Wiesner wrote his thesis, there was no device operating in which the phase coherence of a two-state system was preserved for longer than about a second. | ||
==Outline== | ==Outline== | ||
Let the money have twenty isolated systems <math>S_i\in\{a, b, \alpha, \beta\}, i=1,...,20</math>. The | Let the money have twenty isolated systems <math>S_i\in\{a, b, \alpha, \beta\}, i=1,...,20</math>. | ||
* The Mint creates two random binary sequences of twenty digits <math>M_i,N_i\in\{0,1\}</math> where <math>i=1,...,20</math>. Then, two-state systems are placed in one of four states <math>a, b, \alpha, \beta</math>. | |||
# Bank prepares a pair of orthonormal base states for each state system. Then the two-state system is located in one of four states <math>a, b, \alpha, \beta</math> | # Bank prepares a pair of orthonormal base states for each state system. Then the two-state system is located in one of four states <math>a, b, \alpha, \beta</math> | ||
# The bank records all polarizations and their serial numbers. On the banknote/quantum money the serial number | # The bank records all polarizations and their serial numbers. On the banknote/quantum money the serial number is plain, while polarizations are kept hidden. | ||
# If the money is returned to the | # If the money is returned to the Mint, it checks whether each isolated system is still in its initial state or not. | ||
Note that since no one except the Mint knows <math>M_i</math> and <math>N_i</math>, even if someone copies the money, he cannot recover the polarization. | Note that since no one except the Mint knows <math>M_i</math> and <math>N_i</math>, even if someone copies the money, he cannot recover the polarization. | ||
==Notation== | ==Notation== | ||
*<math>S_i</math>= Isolated system | *<math>S_i</math>= Isolated system | ||