Support for OpenQASM on different Braket Devices - Amazon Braket
Supported Operations, Results and Result Types with OpenQASM

Support for OpenQASM on different Braket Devices

For devices supporting OpenQASM 3.0, the action field supports a new action through the GetDevice response, as shown in the following example for the Rigetti and IonQ devices.

//OpenQASM as available with the Rigetti device capabilities
{
    "braketSchemaHeader": {
        "name": "braket.device_schema.rigetti.rigetti_device_capabilities",
        "version": "1"
    },
    "service": {...},
    "action": {
        "braket.ir.jaqcd.program": {...},
        "braket.ir.openqasm.program": {
            "actionType": "braket.ir.openqasm.program",
            "version": [
                "1"
            ],
            ….
        }
    }
}

//OpenQASM as available with the IonQ device capabilities
{
    "braketSchemaHeader": {
        "name": "braket.device_schema.ionq.ionq_device_capabilities",
        "version": "1"
    },
    "service": {...},
    "action": {
        "braket.ir.jaqcd.program": {...},
        "braket.ir.openqasm.program": {
            "actionType": "braket.ir.openqasm.program",
            "version": [
                "1"
            ],
            ….
        }
    }
}

For devices that support pulse control, the pulse field is displayed in the GetDevice response. The following example show this pulse field for the Rigetti device.

// Rigetti
{
  "pulse": {
    "braketSchemaHeader": {
      "name": "braket.device_schema.pulse.pulse_device_action_properties",
      "version": "1"
    },
    "supportedQhpTemplateWaveforms": {
      "constant": {
        "functionName": "constant",
        "arguments": [
          {
            "name": "length",
            "type": "float",
            "optional": false
          },
          {
            "name": "iq",
            "type": "complex",
            "optional": false
          }
        ]
      },
      ...
    },
    "ports": {
      "q0_ff": {
        "portId": "q0_ff",
        "direction": "tx",
        "portType": "ff",
        "dt": 1e-9,
        "centerFrequencies": [
          375000000
        ]
      },
      ...
    },
    "supportedFunctions": {
      "shift_phase": {
        "functionName": "shift_phase",
        "arguments": [
          {
            "name": "frame",
            "type": "frame",
            "optional": false
          },
          {
            "name": "phase",
            "type": "float",
            "optional": false
          }
        ]
      },
     ...
    },
    "frames": {
      "q0_q1_cphase_frame": {
        "frameId": "q0_q1_cphase_frame",
        "portId": "q0_ff",
        "frequency": 462475694.24460185,
        "centerFrequency": 375000000,
        "phase": 0,
        "associatedGate": "cphase",
        "qubitMappings": [
          0,
          1
        ]
      },
      ...
    },
    "supportsLocalPulseElements": false,
    "supportsDynamicFrames": false,
    "supportsNonNativeGatesWithPulses": false,
    "validationParameters": {
      "MAX_SCALE": 4,
      "MAX_AMPLITUDE": 1,
      "PERMITTED_FREQUENCY_DIFFERENCE": 400000000
    }
  }
}

The preceding fields detail the following:

Ports:

Describes pre-made external (extern) device ports declared on the QPU in addition to the associated properties of the given port. All ports listed in this structure are pre-declared as valid identifiers within the OpenQASM 3.0 program submitted by the user. The additional properties for a port include:

  • Port id (portId)

    • The port name declared as an identifier in OpenQASM 3.0.

  • Direction (direction)

    • The direction of the port. Drive ports transmit pulses (direction “tx”), while measurement ports receive pulses (direction “rx”).

  • Port type (portType)

    • The type of action for which this port is responsible (for example, drive, capture, or ff - fast-flux).

  • Dt (dt)

    • The time in seconds that represents a single sample time step on the given port.

  • Qubit mappings (qubitMappings)

    • The qubits associated with the given port.

  • Center frequencies (centerFrequencies)

    • A list of the associated center frequencies for all pre-declared or user-defined frames on the port. For more information, refer to Frames.

  • QHP Specific Properties (qhpSpecificProperties)

    • An optional map detailing existing properties about the port specific to the QHP.

Frames:

Describes pre-made external frames declared on the QPU as well as associated properties about the frames. All frames listed in this structure are pre-declared as valid identifiers within the OpenQASM 3.0 program submitted by the user. The additional properties for a frame include:

  • Frame Id (frameId)

    • The frame name declared as an identifier in OpenQASM 3.0.

  • Port Id (portId)

    • The associated hardware port for the frame.

  • Frequency (frequency)

    • The default initial frequency of the frame.

  • Center Frequency (centerFrequency)

    • The center of the frequency bandwidth for the frame. Typically, frames may only be adjusted to a certain bandwidth around the center frequency. As a result, frequency adjustments should stay within a given delta of the center frequency. You can find the bandwidth value in the validation parameters.

  • Phase (phase)

    • The default initial phase of the frame.

  • Associated Gate (associatedGate)

    • The gates associated with the given frame.

  • Qubit Mappings (qubitMappings)

    • The qubits associated with the given frame.

  • QHP Specific Properties (qhpSpecificProperties)

    • An optional map detailing existing properties about the frame specific to the QHP.

SupportsDynamicFrames:

Describes whether or not a frame can be declared in cal or defcal blocks through the OpenPulse newframe function. If this is false, only frames listed in the frame structure may be used within the program.

SupportedFunctions:

Describes the OpenPulse functions that are supported for the device in addition to the associated arguments, argument types, and return types for the given functions. To see examples of using the OpenPulse functions, see the OpenPulse specification. At this time, Braket supports:

  • shift_phase

    • Shifts the phase of a frame by a specified value

  • set_phase

    • Sets the phase of frame to the specified value

  • swap_phases

    • Swaps the phases between two frames.

  • shift_frequency

    • Shifts the frequency of a frame by a specified value

  • set_frequency

    • Sets the frequency of frame to the specified value

  • play

    • Schedules a waveform

  • capture_v0

    • Returns the value on a capture frame to a bit register

SupportedQhpTemplateWaveforms:

Describes the pre-built waveform functions available on the device and the associated arguments and types. By default, Braket Pulse offers pre-built waveform routines on all devices, which are:

Constant

Mathematical equation showing a constant function with parameters t, tau, and iq where the output is always equal to iq.

τ is the length of the waveform and iq is a complex number.

def constant(length, iq)

Gaussian

Mathematical equation showing the Gaussian function with parameters t, tau, sigma, A=1, and ZaE=0.

τ is the length of the waveform, σ is the width of the Gaussian, and A is the amplitude. If setting ZaE to True, the Gaussian is offset and rescaled such that it is equal to zero at the start and end of the waveform, and reaches A at maximum.

def gaussian(length, sigma, amplitude=1, zero_at_edges=False)

DRAG Gaussian

Mathematical equation for DRAG Gaussian distribution with parameters t, tau, sigma, beta, A=1, and ZaE=0.

τ is the length of the waveform, σ is the width of the gaussian, β is a free parameter, and A is the amplitude. If setting ZaE to True, the Derivative Removal by Adiabatic Gate (DRAG) Gaussian is offset and rescaled such that it is equal to zero at the start and end of the waveform, and the real part reaches A at maximum. For more information about the DRAG waveform, see the paper Simple Pulses for Elimination of Leakage in Weakly Nonlinear Qubits.

def drag_gaussian(length, sigma, beta, amplitude=1, zero_at_edges=False)

Erf Square

Mathematical equation for Erf Square distribution with parameters t, Length, Width, sigma, A=1, and ZaE=0.

Where L is the length, W is the width of the waveform, σ defines how fast the edges rise and fall, t1​=(L−W)/2 and t22=(L+W)/2, A is the amplitude. If setting ZaE to True, the Gaussian is offset and rescaled such that it is equal to zero at the start and end of the waveform, and reaches A at maximum. The following equation is the rescaled version of the waveform.

Mathematical equation for the rescaled Erf Square distribution with parameters ZaE=1.

Where a=erf(W/2σ)and b=erf(−t1​/σ)/2+erf(t2​/σ)/2.

def erf_square(length, width, sigma, amplitude=1, zero_at_edges=False)

SupportsLocalPulseElements:

Describes whether or not pulse elements, such as ports, frames, and waveforms may be defined locally in defcal blocks. If the value is false, elements must be defined in cal blocks.

SupportsNonNativeGatesWithPulses:

Describes whether we can or cannot use non-native gates in combination with pulse programs. For example, we can’t use a non-native gate like an H gate in a program without first defining the gate through defcal for the used qubit. You can find the list of native gates nativeGateSet key under the device capabilities.

ValidationParameters:

Describes pulse element validation boundaries, including:

  • Maximum Scale / Maximum Amplitude values for waveforms (arbitrary and pre-built)

  • Maximum frequency bandwidth from supplied center frequency in Hz

  • Minimum pulse length/duration in seconds

  • Maximum pulse length/duration in seconds

Supported Operations, Results and Result Types with OpenQASM

To find out which OpenQASM 3.0 features each device supports, you can refer to the braket.ir.openqasm.program key in the action field on the device capabilities output. For example, the following are the supported operations and result types available for the Braket State Vector simulator SV1.

...
  "action": {
    "braket.ir.jaqcd.program": {
      ...
    },
 "braket.ir.openqasm.program": {
      "version": [
        "1.0"
      ],
      "actionType": "braket.ir.openqasm.program",
      "supportedOperations": [
        "ccnot",
        "cnot",
        "cphaseshift",
        "cphaseshift00",
        "cphaseshift01",
        "cphaseshift10",
        "cswap",
        "cy",
        "cz",
        "h",
        "i",
        "iswap",
        "pswap",
        "phaseshift",
        "rx",
        "ry",
        "rz",
        "s",
        "si",
        "swap",
        "t",
        "ti",
        "v",
        "vi",
        "x",
        "xx",
        "xy",
        "y",
        "yy",
        "z",
        "zz"
      ],
      "supportedPragmas": [
        "braket_unitary_matrix"
      ],
      "forbiddenPragmas": [],
      "maximumQubitArrays": 1,
      "maximumClassicalArrays": 1,
      "forbiddenArrayOperations": [
        "concatenation",
        "negativeIndex",
        "range",
        "rangeWithStep",
        "slicing",
        "selection"
      ],
      "requiresAllQubitsMeasurement": true,
      "supportsPhysicalQubits": false,
      "requiresContiguousQubitIndices": true,
      "disabledQubitRewiringSupported": false,
      "supportedResultTypes": [
        {
          "name": "Sample",
          "observables": [
            "x",
            "y",
            "z",
            "h",
            "i",
            "hermitian"
          ],
          "minShots": 1,
          "maxShots": 100000
        },
        {
          "name": "Expectation",
          "observables": [
            "x",
            "y",
            "z",
            "h",
            "i",
            "hermitian"
          ],
          "minShots": 0,
          "maxShots": 100000
        },
        {
          "name": "Variance",
          "observables": [
            "x",
            "y",
            "z",
            "h",
            "i",
            "hermitian"
          ],
          "minShots": 0,
          "maxShots": 100000
        },
        {
          "name": "Probability",
          "minShots": 1,
          "maxShots": 100000
        },
        {
          "name": "Amplitude",
          "minShots": 0,
          "maxShots": 0
        }
        {
          "name": "AdjointGradient",
          "minShots": 0,
          "maxShots": 0
        }
      ]
    }
  },
...