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A210532
Minimum number of observables that need to be measured in order to uniquely determine an n-dimensional quantum state that is known a priori to be pure.
0
3, 7, 9, 15, 17, 22
OFFSET
2,1
LINKS
Teiko Heinosaari, Luca Mazzarella, and Michael M. Wolf, Quantum Tomography under Prior Information. Communications in Mathematical Physics, 318:355-374, 2013.
FORMULA
23 <= a(8) <= 24
4n - 5 - log_2(n) <= a(n) <= 4n - 5 for all n >= 2. More precise bounds are given in the Heinosaari paper.
EXAMPLE
In the n = 2 case, you need to measure all a(2) = 3 linearly independent observables (e.g., the Pauli X, Y, and Z operators) in order to uniquely specify all pure states.
CROSSREFS
Sequence in context: A199919 A346303 A178207 * A110872 A032424 A280861
KEYWORD
nonn,more
AUTHOR
Nathaniel Johnston, Jan 28 2013
STATUS
approved