Quantum Computer Gates

This is a Python implementation of the exercises suggested in the paper Undergraduate computational physics projects on quantum computing (Can1) The original code was written by my son James Hurford-Reynolds. I have refactored his code to make it easier to reuse and added addtional gates beyond his original project. The code supports a simple quantum gate arrangement language in json with provision for repeating sets of gates. For a more extensive and powerful implementation of quantum circuits then check out QuTiP

Explanation of Project

The following modules are part of the project:

Module	Purpose	Dependency
register	Implementation of Qubits as a quantum register and quantum gates and oeprators.	numpy 1.16.5
main	Google serverless function to run quantum program.	flask 1.0.2
register_test	Pyunit tests for register.	numpy 1.16.5
main_test	Pyunit tests for main.	flask 1.0.2
mock_extension	Extensions to Mock to support percentage based error checking.	flask 1.0.2

Quantum Program Format

The execute function in the register module and the quantum_http function in the main module both have the same interface of receivng a JSON program description and returning a JSON response.

Request Format

The input json document has the following format

{
  "num_qbits" : 3,
  "num_measures" : 100,
  "initial_vector" : [1.0, 0, 0, 0, 0, 0, 0, 0],
  "operations" : [
    { "op" : "H", "args" : {"qbit" : 3}},
    { "op" : "P", "args" : {"qbit" : 3, "theta" : 0.0}},
    { "op" : "Repeat", "args" : {"count" : 2, "operations" : [
              {"op" : "H", "args" : {"qbit" : 1}},
              {"op" : "P", "args" : {"qbit": 3, "theta": 3.14159}}
      ]}
    }
  ]
}

• num_qbits is the number of Qubits in the register.
• num_measures is the number of measurements to take at the end of the program.
• initial_vector is the initial input vector and should be 2^num_qbits long
• operations is the sequence of gates and operations to apply to the input.
  • Apply Hadamard Gate
    • op H
    • qbit Qubit to apply to
  • Apply Phase Shift gate
    • op P
    • qbit Qubit to apply to
    • theta Phase shift in radians
  • Apply Pauli X gate
    • op X
    • qbit Qubit to apply to
  • Apply Pauli Y gate
    • op Y
    • qbit Qubit to apply to
  • Apply Pauli Z gate
    • op Z
    • qbit Qubit to apply to
  • Apply J gate
    • op J
  • Apply oracle
    • op O
    • desired_State Desired state to find
  • Repeat operations
    • op Repeat
    • count Number of times to repeat operations
    • operations Operations to apply

Response Format

The output json document has the following format

{
  "final_vector" : [1.0, 0, 0, 0, 0, 0, 0, 0],
  "states" : { "|00100>":50.0, "|00001>":50.0}
}

• final_vector out register values
• states result of sampling output vector

To Do

• Add support for controlled gate (single qubit control)
• Refactor to support pre-calculating quantum gate tensor for optimisation of repeated use of same circuit
• Implement QASM
• Add support for mathematical and physical constants, especially π and ℏ.

References

Can1: Undergraduate computational physics projects on quantum computing : D. Candela : American Journal of Physics 83, 688 (2015); doi: 10.1119/1.4922296