Language

OpenQASM refers to the extended language we now describe, specifically OpenQASM Version 3.0.

The human-readable form of OpenQASM is a simple, case-sensitive textual language. Statements are separated by semicolons and whitespace is ignored.

In other respects, OpenQASM possesses a dual nature as an assembly language and as a hardware description language.

Appendix [app:summary] summarizes the language statements, Appendix [app:grammar] specifies the grammar, and Appendix [app:semantics] gives formal semantics.

• Comments
• Version string
• Included files
• Types and Casting
  • Identifiers
  • Variables
  • Quantum types
    • Qubits
    • Physical Qubits
  • Classical scalar types
    • Classical bits and registers
    • Integers
    • Floating point numbers
    • Void type
    • Angles
    • Complex numbers
    • Boolean types
  • Compile-time constants
    • Built-in constants
    • Built-in constant expression functions
  • Literals
  • Arrays
  • Types related to timing
    • Duration
    • Stretch
  • Aliasing
  • Index sets and slicing
  • Register concatenation and slicing
  • Classical value bit slicing
  • Array concatenation and slicing
  • Casting specifics
    • Allowed casts
    • Casting from bool
    • Casting from int/uint
    • Casting from float
    • Casting from angle
    • Casting from bit
    • Converting duration to other types
• Gates
  • Applying gates
    • Broadcasting
    • Parameterized gates
  • Defining gates
    • Hierarchical gates definitions
    • Quantum gate modifiers
      • Control modifiers
      • Inverse modifier
      • Power modifier
    • Built-in gates
      • Built-in single-qubit gate U
      • Global phase gate gphase
  • Relation of the built-in gates to hardware-native gates
• Built-in quantum instructions
  • Initialization
  • Measurement
• Classical instructions
  • Low-level classical instructions
    • Generalities
    • Classical bits and registers
    • Comparison (Boolean) Instructions
    • Integers
    • Angles
    • Floating-point numbers
    • Complex numbers
    • Evaluation order
    • Looping and branching
      • If-else statements
      • For loops
      • While loops
      • Breaking and continuing loops
      • Terminating the program early
  • Extern function calls
  • Further reserved keywords
• Subroutines
  • Arrays in subroutines
• Scoping of variables
  • Global scope
  • Subroutine and gate scope
  • Block scope
• Directives
  • Pragmas
  • Annotations
• Input/output
• Circuit timing
  • Duration and stretch types
  • Operations on durations
  • Delays (and other duration-based instructions)
  • Boxed expressions
  • Barrier instruction
• Pulse-level descriptions of gates and measurement
  • Inline calibration blocks
  • Restrictions on defcal bodies
  • Calibrations in practice
• OpenPulse Grammar
  • Ports
  • Frames
    • Frame Initialization
    • Frame Manipulation
  • Waveforms
  • Play instruction
  • Capture Instruction
  • Timing
    • Initial Time
    • Delay
    • Play and Capture
    • Barrier
    • Phase tracking
    • Collisions
  • Examples
    • Rabi Spectroscopy
    • Cross-resonance gate
    • Geometric gate
    • Neutral atoms
    • Multiplexed readout and capture
    • Open Questions