Operations

An Op references qubits by numeric gate index. Scotty provides Gate and Measure operations.

Gates

Gates transform the state vector. Their order in a circuit matters. See Standard Gates and Modifiers and Custom Gates.

Measurements

import scotty.quantum._
import scotty.quantum.gate.StandardGate._
import scotty.simulator.QuantumSimulator

val simulator = QuantumSimulator()
val circuit = Circuit(H(0), CNOT(0, 1), Measure(0))
val result: State = simulator.run(circuit)
val description = result match {
  case _: Superposition => "not measured"
  case c: Collapsed => s"measured: ${c.toBinary}"
}

Although Measure(0) names one qubit, QuantumSimulator detects the presence of any measurement, applies all gates, then samples the whole register. The position and target of Measure do not introduce an intermediate or partial measurement.

For example, the following returns "1" deterministically, because X(0) runs before measurement:

val deferred = simulator.run(Circuit(Measure(0), X(0)))
assert(deferred.asInstanceOf[Collapsed].toBinary == "1")

For a final whole-register measurement, prefer the explicit method:

val measured: Collapsed = simulator.runAndMeasure(Circuit(H(0), CNOT(0, 1)))
assert(Set("00", "11").contains(measured.toBinary))

Do not use these operations to model protocols requiring intermediate measurement results to control subsequent gates.