Fix global phase in OneQubitEulerDecomposer using PSX and ZSX basis and in Diagonal gate #5474
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mtreinish
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Changelog: Bugfix
kdk
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Dec 10, 2020
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Will this resolve #5453 ? |
georgios-ts
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It might be good to add test conditions for angle arguments which use shorter decompositions. |
ewinston
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Jan 18, 2021
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…nd in Diagonal gate (#5474) * fix global phase in OneQubitEulerDecomposer using PSX and ZSX basis * minor fixes * update tests * update randomized test * set global_phase=True * track global phase in diagonal gate * fix dimension * add test for special cases of zsx psx decomposition. * linting Co-authored-by: ewinston <[email protected]> Co-authored-by: Kevin Krsulich <[email protected]> (cherry picked from commit e98d456)
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…nd in Diagonal gate (#5474) (#5652) * fix global phase in OneQubitEulerDecomposer using PSX and ZSX basis * minor fixes * update tests * update randomized test * set global_phase=True * track global phase in diagonal gate * fix dimension * add test for special cases of zsx psx decomposition. * linting Co-authored-by: ewinston <[email protected]> Co-authored-by: Kevin Krsulich <[email protected]> (cherry picked from commit e98d456) Co-authored-by: georgios-ts <[email protected]> Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
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Summary
PSXandZSXbasis use the same parameters asU1Xbasis. This means that there is api / 4global phase discrepancy every time we use anSXgate instead of anRx(pi/2)gate andphi / 2every time we use aRz(phi)instead of aP(phi).Not resolved in #5248
Tracks also global phase in
diagonalgate and resolves #5453.Details and comments
Fixes also the global phase when simplifications can be made since:
Phase(phi).SX.Phase(pi).SX.Phase(lam)=exp(i pi / 2).Phase(phi + lam + pi)Phase(phi).SX.Phase(-pi).SX.Phase(lam)=exp(i pi / 2).Phase(phi + lam - pi)and
Phase(phi).SX.Phase(pi / 2).SX.Phase(lam)=Phase(phi + pi / 2).SX.Phase(lam + pi / 2)Phase(phi).SX.Phase(-pi / 2).SX.Phase(lam)=exp(i pi / 2).Phase(phi - pi / 2).SX.Phase(lam - pi / 2)and
Phase(phi).SX.Phase(3pi / 2).SX.Phase(lam)=exp(i pi / 2).Phase(phi + 3pi / 2).SX.Phase(lam + 3pi / 2)Phase(phi).SX.Phase(-3pi / 2).SX.Phase(lam)=Phase(phi - 3pi / 2).SX.Phase(lam - 3pi / 2)