Add support for optimized multi-controlled gates #124
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This looks good. Can you add a few tests? Not sure if you do your tests with manual Qobj or with Terra. If Terra, then we need to wait until Terra can generate these qobj instructions.
Edit: actually, you can already define any gate you want in terra.
Is it possible to have cswap (Fredking Gate), as well as mcswap? Not blocking for this PR.
| // Calculate the permutation positions for the last qubit. | ||
| const size_t N = qubits.size(); | ||
| const size_t pos0 = MASKS[N - 1]; | ||
| const size_t pos1 = MASKS[N]; | ||
| // Lambda function for CNOT gate |
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| // Lambda function for CNOT gate | |
| // Lambda function for mcx gate |
| const size_t pos0 = MASKS[N - 1]; | ||
| const size_t pos1 = MASKS[N]; | ||
| const complex_t I(0., 1.); | ||
| // Lambda function for CNOT gate |
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| // Lambda function for CNOT gate | |
| // Lambda function for mcy gate |
| const size_t N = qubits.size(); | ||
| const size_t pos0 = MASKS[N - 1]; | ||
| const size_t pos1 = MASKS[N]; | ||
| // Lambda function for CNOT gate |
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| // Lambda function for CNOT gate | |
| // Lambda function for mcu gate |
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@ajavadia shouldnt be too hard to add a cswap and mcswap, I'll do it in a follow up PR though |
chriseclectic
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@chriseclectic looks good to me! |
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The application of these functions for regular cx, ccx, cz, swap are already covered in current tests, but I want to wait till terra has a stable way of adding custom gates before adding additional tests, (this is tracked in issue #132). |
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Any one know how to use this multiple controlled gates inside qiskit python? |
* add multi-controlled pauli gates * implement cx, cz as mcx, mcz * add multi controlled u1,u2,u3 gates * fixup indexes refs * update changelog
Summary
Adds support for multi-controller x,y,z,u1,u2,u3 gates to the statevector QasmSimulator, StatevectorSimulator and UnitarySimulator.
These gates have an optimized implementation making them faster to execute than the gate being unrolled into a basis of
cxand single qubit gates.Closes #127
Details and comments
These gates are passed in as (N+1)-qubit qobj instructions such as:
{"name": "mcx", "qubits": [c0, c1,...,cn, target]}where the first
Nqubits are the controls, and the last qubit is the target.For the controlled
u1,u2,u3gates the instruction includes the same parameters as for the single qubit gates. Eg:{"name": "mcu3", "qubits": [c0, c1,...,cn, target], "params": [theta, phi, lam]}TODO: