QuIPS: Quantum Information Processing System

Bertrand Russel said

"War does not determine who is right, only who is left".

We can interpret this as,

Quantum Mechanics does not determine which state is right, only which operators are to the left.

That motto will be the starting point of this project; modeling a quantum computer as a sequence of gate operations on an initital tensor product state of N Qubits.

Installation

To install:

• clone this repository
• in julia REPL of cloned directory:
  • enter pkg mode with ]
  • run pkg> activate . to activate directory environment
  • run pkg> instantiate to set up package

Now package can be used with using QuIPS in julia scripts (quips) or right in REPL.

Usage

A quantum compuatation begins with specifying a list of successive gates and measurements. We shall call this quantum information program, or process, or whatever, a quip. Additionally, the number of qubits, N must be specified.

As an example of what a quip currently looks like, here is a Julia vector containing the instructions to put 2 qubits into an entangled Bell singlet state and measure them, the results should be correlated.

quip = [
    (:H, 2),
    (:CX, (2, 1)),
    (:MEASURE, 1),
    (:MEASURE, 2)
]

Here, :CX = :CNOT, both are allowed, but I prefer :CX as it flows with the naming convention and differentiates quantum compuation, the X gate, from the classical compuation, the NOT gate. "NOT" is ill defined.

A quip is currently formatted as a Julia vector of tuples, where each tuple contains a symbol specifying the desired operation, optionally a parameter for parameterized gates and finally the index(es) of the targeted qubit(s), just the index or an array of of indices for multi qubit gates.

random_quip = [
    (:RX, 3.14, 1),
    (:Y, 2),
    (:CCZ, (3, 2, 4)),
    (:H, 1),
    (:CY, (3, 2))
    (:CCH, (2, 1, 3))
    (:PHASE, 0.5*3.14, 3)
]

Once we have our quip specified, we need to compile it, and the number of qubits we want to work with, into a Quantum Circuit, for our QVM to work with. Here we will just run the quantum computer and that looks like this.

QC = QCircuit(quip, 2)
run!(QC)

We can then access information stored in QC like QC.wfn.

To-Do

general

• jupyter lab
• google colab

syntax

• macros
• visualisations
• run! functionality

algorithms

• ising
• QFFT
• schur transform

formalisms

• density operator
  • artificial noise
• path integral

optimizations

• GPU
• graph state
  • Gottesman-Knill theorem
• clifford group