NV-Center Diamond Quantum Thermometer

Sample Conditions

True temperature T 300.0 K

Bias field B_z 0.0 mT

Averaged sweeps N 4

ODMR Spectrum

Measurement

Measured D(T)

2870.0 MHz

Inferred T

300.0 K

Error vs true T

0 mK

How it works

A nitrogen-vacancy (NV) center is a substitutional nitrogen atom next to a missing carbon in diamond. Its ground state is a spin-1 triplet with a zero-field splitting D between the m_s=0 and m_s=±1 sublevels, driven and read out optically (ODMR):

D(T) = D₀ − a·(T − T₀)
D₀ = 2870.0 MHz,  T₀ = 300 K,  a = 0.0742 MHz/K

Optically-detected fluorescence vs microwave freq f:
PL(f) = PL₀·[1 − C·(L(f−f₋,Γ) + L(f−f₊,Γ))]
f± = D(T) ± γₑ·B_z ,  γₑ ≈ 28.02 MHz/mT (electron spin)

True temperature — the hidden real temperature of the diamond; the sensor never sees this number directly, only the fluorescence dip.
Bias field — a static B_z Zeeman-splits the single dip into a symmetric pair around D(T); their midpoint still reports D(T) cleanly, which is why NV thermometry works even in a stray field.
Averaged sweeps N — each sweep is shot-noise limited; averaging N repeats shrinks the fluorescence noise by 1/√N, the same scaling that sets the sensor's mK-level precision in real devices.
The inferred temperature comes from a weighted-centroid fit of the dip(s) in the averaged spectrum, then inverting D(T) — exactly the estimator a real ODMR thermometry pipeline uses.

Real-world relevance: NV-diamond thermometers already map temperature inside living cells and on chip hotspots at sub-micron resolution and sub-degree precision — a distinct use of the same NV spin that magnetometers exploit via the Zeeman shift instead of this thermal shift of D.

Carbon lattice Nitrogen (N) Vacancy / spin

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