Welcome to the Docs for Forest and pyQuil!

Overview

pyQuil is part of the Rigetti Forest toolkit for quantum programming in the cloud. If you are interested in obtaining an API key for the beta, please reach out by signing up here. We look forward to hearing from you.

pyQuil is an open source Python library developed at Rigetti Computing that constructs programs for quantum computers. The source is hosted on GitHub. More concretely, pyQuil produces programs in the Quantum Instruction Language (Quil). For a full description of Quil, please refer to the whitepaper A Practical Quantum Instruction Set Architecture. [1] Quil is an opinionated quantum instruction language — its basic belief is that in the near term quantum computers will operate as coprocessors, working in concert with traditional CPUs. This means that Quil is designed to execute on a Quantum Abstract Machine that has a shared classical/quantum architecture at its core.

Quil programs can be executed on a cloud-based Quantum Virtual Machine (QVM). This is a classical simulation of a quantum processor that can simulate various qubit operations. The default access key allows you to run simulations of up to 26 qubits. These simulations can be run through either synchronous API calls, or through an asynchronous job queue for larger programs. More information about the QVM can be found in the The Quantum Virtual Machine (QVM).

In addition to the QVM, we offer the ability to run programs on our superconducting quantum processors, or Quantum Processing Units (QPUs), at our lab in Berkeley, California. To request upgraded access to our 19Q QPU, please fill out the request form with a brief summary of what you hope to use it for. For more information on QPUs, check out The Quantum Processing Unit (QPU).

If you are already familiar with quantum computing, then feel free to proceed to Installation and Getting Started. Otherwise, take a look at our Introduction to Quantum Computing, where we use Quil introduce the basics of quantum computing and the Quantum Abstract Machine on which it runs.

[1]	https://arxiv.org/abs/1608.03355

Contents

• Introduction to Quantum Computing
  • From Bit to Qubit
    • Probabilistic Bits as Vector Spaces
    • Dirac Notation
    • Multiple Probabilistic Bits
    • Qubits
    • An Important Distinction
    • Some Code
  • Qubit Operations
    • Pauli Operators
    • Multi-Qubit Operations
  • The Quantum Abstract Machine
    • Qubit Measurements
    • Classical/Quantum Interaction
    • Classical Control
    • Example: The Probabilistic Halting Problem
  • Next Steps
• Installation and Getting Started
  • Connecting to Rigetti Forest
  • Getting Started
  • Your First Quantum Program
• The Basics: Programs and Gates
  • Some Program Construction Features
  • Fixing a Mistaken Instruction
  • The Standard Gate Set
  • Defining New Gates
  • Defining Parametric Gates
• Advanced Usage
  • Quantum Fourier Transform (QFT)
  • Classical Control Flow
  • Parametric Depolarizing Noise
  • Parametric Programs
  • Pauli Operator Algebra
• Exercises
  • Exercise 1: Quantum Dice
  • Exercise 2: Controlled Gates
  • Exercise 3: Grover’s Algorithm
• The Quantum Virtual Machine (QVM)
  • Using the QVM
    • The .run(...) method
    • The .wavefunction(...) method
  • Multi-Qubit Basis Enumeration
  • Examples of Quantum Programs
    • Meyer-Penny Game
    • Exercises
• The Quantum Processing Unit (QPU)
  • Using the QPU
    • Accessing available devices with get_devices()
    • Execution on the QPU
    • Getting QPU Information from the Device Class
    • Simulating the QPU using the QVM
    • Retune Interruptions
  • Agave QPU Properties
    • 1-Qubit Gate Performance
    • Qubit-Qubit Coupling
    • 2-Qubit Gate Performance
  • Acorn QPU Properties – CURRENTLY UNAVAILABLE
• The Quil Compiler
  • Expectations for Program Contents
  • Interacting with the Compiler
  • Region-specific compiler features through PRAGMA
    • Preserved regions
    • Parallelizable regions
    • Rewirings
  • Common Error Messages
• Using Qubit Placeholders
  • Register
• Noise and Quantum Computation
  • Modeling Noisy Quantum Gates
    • Pure States vs. Mixed States
    • Quantum Gate Errors
    • Why Do Incoherent Errors Happen?
    • A Toy Model
  • Noisy Gates on the Rigetti QVM
    • Getting Started
    • Example 1: Amplitude Damping
    • Example 2: Dephased CZ-gate
  • Adding Decoherence Noise
    • The Task
    • The Idiomatic PyQuil Program
    • The Compiled Program
    • Scan Over Noise Parameters
    • Plot the Results
  • Modeling Readout Noise
    • Qubit Measurements
  • Working with Readout Noise
    • Example 1: Rabi Sequence with Noisy Readout
    • Example 2: Estimate the Assignment Probabilities
    • Example 3: Correct for Noisy Readout
• Source Code Documentation
  • pyquil.api
  • pyquil.device
  • pyquil.gates
  • pyquil.noise
  • pyquil.parametric
  • pyquil.paulis
  • pyquil.quil
  • pyquil.quilbase
  • pyquil.slot
  • pyquil.wavefunction
• Changelog
  • v1.9 (June 6, 2018)
    • Qubit placeholders
    • Randomized benchmarking sequence generation
    • Ease of Use
    • Supported versions of Python
    • Bug fixes

Indices and Tables

• Index
• Module Index
• Search Page