jgarte / qd-py

Quantum† Python

Quantum† Python

A tiny Python simulator for ideal quantum computers.

How To Run

For now:

python -m src.gates

Questions

• How do we “split” or copy a qubit?

Examples

Initial

Minimum circuit: quantum coin flip

Initiate a qubit, apply Hadamard gate, measure.

Aspirational

(because I haven’t the foggiest idea how to accomplish this yet)

Quantum Rock-Paper-Scissors

Two third-parties send us a single qubit, which encodes a sign (rock, paper, scissors.) The quantum circuit informs us which sign each party threw, and who wins, according to the classic rules.

Or, a variant: the circuit only shows who wins, without revealing which signs were thrown. Does this variant lend itself to a more elegant expression or simpler circuit? Does this concept bear any resemblance to quantum key negotiation?

Big Picture

What is the “hello world!” of quantum computing? How do we represent human-level knowledge in a quantum system?

Begging further questions:

• can a quantum system drive a six-segment display?
• or what does a human-level readout look like?
• do we only care about “measurements” in the final sense, or do we consider outputs that come from intermediate states?

  If the answer is that we only care about measurements, then we have to collapse at some point into classical bits in order to give a readout.

  If we are willing to consider quantum-informational outputs that couldn’t actually be measured but might nonetheless be interesting to the learner, then we might conceive of some kind of intermediate user output display.

  For example, suppose we were to split up the state space into 26 segments, each representing a letter. Then we can select a letter by rotating the |0> (zero ket) by 1/26 radians for each letter of the alphabet.

  In addition, can we map from one to the other? Once we’ve conceived of some kind of perhaps-fictitious encoding system that relies on unrealistic level of information about the exact state of a qubit, under what circumstances can we build a quantum circuit that encodes that output in an actually measurable way?