circuit.hpp File Reference

Fluent quantum circuit builder and statevector simulator. More...

#include "quantum/statevector.hpp"
#include <map>
#include <string>
#include <vector>

Go to the source code of this file.

Classes
struct	num::Result
	Measurement outcome from Circuit::run() More...
struct	num::GateView
	Compact gate description used by visualisation code. More...
class	num::Circuit
	Chainable quantum circuit builder. More...

Namespaces
namespace	num

Functions
Circuit	num::bell_pair (int q0=0, int q1=1)
	Bell state |Phi+> = (|00> + |11>)/sqrt2 on qubits q0, q1.
Circuit	num::ghz_state (int n_qubits)
	n-qubit GHZ state (|00...0> + |11...1>)/sqrt2
Circuit	num::qft_circuit (int n_qubits)
	n-qubit Quantum Fourier Transform circuit Applied to |0...0> unless you prepend state-preparation gates.
void	num::print_state (const quantum::Statevector &sv, int n_qubits, real threshold=1e-6)
	Pretty-print a statevector, hiding amplitudes below threshold.

Detailed Description

Fluent quantum circuit builder and statevector simulator.

Provides a chainable Circuit class that reads like a circuit diagram. Gates are recorded and replayed on a statevector on demand, so you can inspect intermediate states (step-through) or sample measurement outcomes.

Quick start

#include "quantum/circuit.hpp"
using num::Circuit;
 
// Bell state
auto sv = Circuit(2).h(0).cx(0,1).statevector();
 
// Grover search (2 qubits, finds |11>)
auto result = Circuit(2)
    .h(0).h(1)
    .cz(0,1)                             // oracle
    .h(0).h(1).x(0).x(1).cz(0,1).x(0).x(1).h(0).h(1)   // diffusion
    .run(4096);
result.print();   // |11>: 4096/4096
 
// QFT on 3 qubits
Circuit qft(3);
qft.x(0)
   .h(2).cp(M_PI/2, 1,2).cp(M_PI/4, 0,2)
   .h(1).cp(M_PI/2, 0,1)
   .h(0).swap(0,2);
qft.print();     // ASCII diagram

Definition in file circuit.hpp.