NMR Analysis tab
The tab shows what the current circuit would look like on a liquid-state NMR quantum computer: the spin sample it runs on, the pulse programme that implements it, the spectrum an acquisition would record, and the state of every spin. It updates on every run and follows the step scrubber of Data Analysis.
Toolbar
| Control | What it does |
|---|---|
| Sample | The spin system, grouped by spin count. Samples with fewer spins than the circuit needs are greyed out. See the sample library. |
| B₀ | Static field: a proton-frequency preset from 60 MHz to 1 GHz, or any value in tesla. |
| B₁ | RF amplitude in millitesla with the resulting proton nutation frequency; sets every pulse length. |
| Shape | Pulse envelope: hard, Gaussian, sinc or Hermite. Shaped pulses are longer for the same flip angle. |
| Channel | The isotope the receiver listens to, with its reference frequency. |
| Readout | "90° pulse, acquire" or "acquire as is". See Readout and spectra. |
| T₁, T₂, LB | Relaxation times in seconds and extra line broadening in hertz; T₂ and LB set the line widths, T₁ and T₂ the acquisition lengths. |
| Reference | The nuclei table at the current field, the conventions, and the sample grid. |
| ⛶ | Fullscreen. Esc leaves it. |
Side panel
- Sample card with the formula, a description and the isotopes present.
- Spins: wire, isotope, chemical shift (editable), reference frequency and the z magnetisation of each spin. Click a row to centre the spectrum on that spin.
- J couplings: every pair with its coupling (editable) and the 1/(2J) period that a CNOT on that pair needs.
- State: purity of the loaded density matrix, the number of lines on the channel and the thermal polarisation at the current field.
Edits apply to the current session; reset restores the library values.
Views
| View | Shows |
|---|---|
| Dashboard | Spectrum, structure, pulse programme and FID side by side. The ⤢ button on any tile opens it on its own. |
| Spectrum | The channel's spectrum in ppm or Hz. Wheel to zoom at the cursor, drag to pan, double-click to fit, click a line for its details. Toggles for spin labels, multiplet markers and integrals; CSV and PNG export. |
| FID | The time signal of the same lines, real and imaginary parts, with dwell time, spectral width and acquisition length. CSV export. |
| Pulse programme | One lane per spin with the RF pulses (height by flip angle, envelope by shape), delays, coupling periods, virtual z rotations and acquisitions of the circuit, plus loop and branch markers. Hover for the numbers, click to pin. |
| Structure | The molecule with the qubit atoms ringed, coupling arcs labelled in hertz, and a hover card per spin. |
| Bloch | The reduced state of every spin as a top-view Bloch vector and a z bar. |
| Levels | The product-state energy levels of up to five spins, their populations, and the channel's transitions drawn stronger where the state holds that coherence. |
How the pulse programme is built
Each gate maps to a pulse fragment: X and Y to 180° pulses, H to a 90°y followed by 180°x, rotations to pulses of that angle, Z-type gates to virtual z rotations, CX and CZ to a refocused coupling period of 1/(2J) between 90° pulses, MEASURE to a readout pulse plus an acquisition. Gates in one column that act on different spins run in parallel. Calls to the NMR library are drawn as their NMR element with the real duration you asked for. A two-spin gate on a pair without a coupling is marked with a red block: it cannot be run on that sample.
Programme settings
A file can carry its own sample, field and readout with the #settings Nmr keys. They are applied when the file is loaded and can be changed on the toolbar afterwards.
Large circuits
The density matrix is kept for up to ten wires. Above that the tab keeps the first ten wires of the state and traces out the rest, and says so on the sample card. The pulse programme always covers the whole circuit.
Related
Data Analysis shares the density-matrix engine and the step scrubber. The stand-alone NMR spectrometer covers conventional chemistry samples, solvents and 2D experiments.