quchip.control.signal_spec

Frame-agnostic drive signal specifications.

This module defines the data a drive emits to describe one scheduled pulse without committing to any specific frame, carrier convention, or engine IR representation. The spec carries ordinary-GHz frequencies and envelope references only — no quchip.engine.ir nodes appear here.

Stage 2 of the engine is the sole consumer that composes a DriveSignalSpec with the resolved rotating frame and the drive channel’s DriveModulation kind to produce the IR-level SignalProgram AST. This keeps drives owning their local Hamiltonians and the engine owning IR assembly, with no legacy fallback path.

Classes

DriveModulation(value)

How a drive channel's operator is time-modulated.

DriveSignalSpec(envelope, start_time, ...)

Frame-agnostic description of one scheduled drive pulse.
class quchip.control.signal_spec.DriveModulation(value)[source]

Bases: Enum

How a drive channel’s operator is time-modulated.

  • SINGLE_TONE — microwave IQ-style carrier mixing. In the lab frame the raw signal is mixed with exp(-i·2π·ν_d·t) and projected to its real part; under RWA the signal is decomposed into co- and counter-rotating components per Fourier band (Krantz et al. 2019, Eq. 89–90).

  • DIRECT_REAL — real-valued baseband coupling (no carrier, no RWA), appropriate for flux-like drives (Koch et al. 2007, Sec. II; Krantz et al. 2019, Sec. V.A on flux tunability).

  • EDGE_PUMP — real pump δ(t) on a modulable coupling’s strength: baseband δ(t) = Re s(t) when the scheduled op has no carrier, single-tone δ(t) = Re[s(t)·e^{-i·2π·ν_d·t}] when it does. The tone is never RWA-split — the coupling’s parametric hook already selected the retained operator structure (Didier et al., PRA 97, 022330 (2018) on parametric gate activation).

The engine dispatches on this tag in a single code path; adding a new modulation kind is an infrastructure change, not a per-drive special case.

SINGLE_TONE = 'single_tone'
DIRECT_REAL = 'direct_real'
EDGE_PUMP = 'edge_pump'
class quchip.control.signal_spec.DriveSignalSpec(envelope, start_time, duration, phase_offset, drive_freq)[source]

Bases: object

Frame-agnostic description of one scheduled drive pulse.

The spec carries everything the engine needs to build the raw line signal and later compose it with the frame + carrier during modulation — expressed in ordinary GHz (frequencies) and ns (times), with no IR references.

Parameters:

  • envelope (BaseEnvelope) – Pulse envelope reference. Its waveform(t) is called at evaluation time; all differentiable pulse parameters live as leaves on the envelope (quchip.control.envelopes).

  • start_time (float) – Onset of the pulse in ns.

  • duration (float) – Envelope duration in ns (the pulse is zero outside [start_time, start_time + duration]).

  • phase_offset (float) – Phase rotation applied to the raw line signal, in radians.

  • drive_freq (float | None) – Microwave carrier frequency in ordinary GHz for DriveModulation.SINGLE_TONE channels; None for baseband (DriveModulation.DIRECT_REAL) drives.

envelope: BaseEnvelope
start_time: float
duration: float
phase_offset: float
drive_freq: float | None