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artiste-qb-net / qubiter

Python tools for reading, writing, compiling, simulating quantum computer circuits. Includes numpy and tensorflow backends. “Quantum Space, the final frontier. These are the voyages of the starship Qubiter. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before.”
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Possible simplification for threaded gradients #35

Open rrtucci opened 5 years ago

rrtucci commented 5 years ago

Stairs circuit is currently defined so that, in its full generality (i.e., where it includes all possible parents for each U(2)), it has as final state, a completely general n-qubit state. The stairs circuit as currently defined uses multi-controlled U(2) gates. Can one replace each U(2) by exp(i*alpha) Ry(beta) for real numbers alpha, beta? Hence reduce from four to two parameters per gate string. This would simplify calculation of derivatives. Would it still produce a completely general n-qubit state at the end?

rrtucci commented 5 years ago

No. But replacing each U(2) by R(t1, t2, t3) with 1 out of the 3 parameters (t1, t2, t3) equal to zero, would work. So you really only need 2 parameters per U(2), not 4.