A single NV electron spin has three textbook behaviours: it flops between 0 and −1 under a microwave (Rabi), it keeps time between two half-pulses and loses it (Ramsey), and it answers a rotated readout (the setting angle). White is the standard curve. Amber is the medium-bound rule: the shared medium makes one draw around the state marker (E, the reference angle), and the spin reads (+), a bright glow, if the draw lands within 90° of the setting, and (−), no glow, if it does not. A (−) from a setting that the draw missed is a flip. The default cloud is the half-cosine distribution (a cosine-weighted lobe) with no free parameter. Click or drag on any curve to see that point as a cloud of shots.
Each dot is one shot of the medium's draw. The shaded half is everything within 90° of the setting arrow; a dot inside it reads 0, bright, (+) (amber); outside it reads −1, dark, (−) (grey), which is a flip. The chance of reading 0 is the share of the cloud inside the shaded half.
| Real control | In the model | Stage |
|---|---|---|
| Green laser resets the spin to 0 | The state marker, E, sits at 0° | 2 |
| Microwave pulse of angle θ (Rabi) | The setting angle is θ, the marker stays at 0°. A longer pulse means a larger θ. | 3 |
| π/2 pulse, wait, π/2 pulse (Ramsey) | The marker starts at 0° and advances with the wait. The second π/2 acts as a fixed setting 180° from the start. Dephasing shows up as shot-to-shot spread in how far the marker advanced. | 3 to 10 |
| Rotate, then read along Z | The setting angle is s. A shot reads 0 if its hidden phase lands within 90° of s. | 10 |
This mapping is a proposal, not something the medium-bound model or standard theory states. In particular, the walkthrough's stage 3 currently sets both electrons to 90° and settles the outcome with the tie rule, which is a different treatment from letting the pulse angle act as a setting.
Vertical axis on every curve: chance of reading 0 (bright). Standard curves: Rabi ½(1 + cos θ); Ramsey ½(1 − e−(τ/T2*)² cos 2πδτ), which starts at 0 because two back-to-back π/2 pulses make a π pulse; rotated readout ½(1 + cos Δ). The Gaussian envelope is the usual shape when the dephasing comes from a slowly changing magnetic environment. Frequencies and times are illustrative, not measured values. Real curves also fall short of 0 and 1 because of initialisation and readout errors.