Getting Started

Installation

Add Scotty to your build.sbt:

libraryDependencies += "xyz.entangled" %% "scotty" % "0.6.0"

Use Scala 2.12 or 2.13. For Maven or Gradle, select the artifact matching your Scala binary version: scotty_2.13 or scotty_2.12. The organization remains xyz.entangled even though the repository has moved to vasinov/scotty.

For example, Maven with Scala 2.13 uses:

<dependency>
  <groupId>xyz.entangled</groupId>
  <artifactId>scotty_2.13</artifactId>
  <version>0.6.0</version>
</dependency>

Create a Bell pair

This complete example prepares two entangled qubits. All qubits start in $|0⟩$ unless you supply a register.

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

implicit val simulator: QuantumContext = QuantumSimulator()
val bell = Circuit(H(0), CNOT(0, 1))
val state = simulator.run(bell)
println(StateProbabilityReader(state).toHumanString)

The two possible basis states have equal probabilities:

00: Amplitude: 0.707+0.000i, P: 50.00%
11: Amplitude: 0.707+0.000i, P: 50.00%

QuantumSimulator implements QuantumContext. Making the context implicit lets the state readers use it. The simulator returns Superposition when the circuit has no measurement operations.

To see individual qubit probabilities, format each reader result:

println(QubitProbabilityReader(state).read.map(_.toHumanString).mkString("\n"))

qubit_0: P(0) = 50.00% P(1) = 50.00%
qubit_1: P(0) = 50.00% P(1) = 50.00%

These marginal probabilities alone do not prove entanglement; the joint state above shows the correlation between the two qubits.

Measure the circuit

val measured = simulator.runAndMeasure(bell)
println(measured.toBinary)

Each run returns either 00 or 11. Repeated runs approach a 50/50 split; an individual run is random.

Set the initial state

val initialized = bell.withRegister("10")

Binary strings are written with the most significant bit on the left. Gate index 0 acts on the rightmost bit of the displayed basis state. See register ordering for the distinction between gate indices and register sequence positions in this release.

Continue with Quantum Context and Simulator.