Separable-state simulation of quantum program code

A method enacted in a computer system to test a quantum program configured for execution on a quantum computer, the method comprising:

• receiving the quantum program;
• representing an evolving quantum state of a qubit register of the quantum computer as an array of complex-valued amplitudes, where each amplitude is associated with an individual qubit of the qubit register, and where the quantum state is separable as a product of individual quantum states of each qubit of the qubit register;
• retrieving from the quantum program one or more instructions corresponding to a quantum circuit;
• adjusting the amplitudes of the array to reflect a change in the quantum state pursuant to execution of the quantum circuit, wherein the change preserves separability of the quantum state as a product of individual quantum states of each qubit of the qubit register;
• and
• computationally exposing, in such form as to be receivable as input to a computer program, one or more of the amplitudes as adjusted.

A method enacted in a computer system to digitally simulate an evolving quantum state of a qubit register of a quantum computer, the method comprising:

• representing the quantum state as an array of complex-valued amplitudes, where each amplitude is associated with an individual qubit of the qubit register, and where the quantum state is separable as a product of mutually non-entangled quantum states of subsets of qubits of the qubit register;
• receiving one or more quantum-program instructions corresponding to a quantum circuit;
• adjusting the amplitudes of the array to reflect a change in the quantum state pursuant to execution of the quantum circuit, wherein the change preserves separability of the quantum state as a product of the mutually non-entangled quantum states of the subsets of qubits of the qubit register;
• and
• computationally outputting, in such form as to be receivable as input to a computer program, one or more of the amplitudes as adjusted.