Quantum mechanics is useless in sensors.

Home page
NV-center, SQUID useless
Protein spin sensor

MRI (= magnetic resonance imaging ) invention relied on experimental observation of nuclear magnetic moments and classical nuclear spin, irrelevant to (useless) quantum mechanical prediction.

(Fig.1)  MRI just measures light pulse whose energy is equal to magnetic energy between external magnetic field and classical proton's magnetic moment, No need of quantum mechanics.

Magnetic resonance imaging (= MRI ) can be explained by classical mechanical proton's spinning that does Not need quantum mechanics.

MRI (= magnetic resonance imaging ) is often said to be caused by quantum mechanics, which is wrong.

We can treat a proton as a classical mechanical particle's spinning, which is different from the unreal electron spin (= a tiny electron must be spinning faster than light to generate the observed magnetic moment ) that is just a classical electron's orbit.

Magnetic energy of classical nuclear spin in MRI

MRI just measures light whose energy is magnetic energy between up and down classical nuclear spins under applied magnetic field, which does Not use quantum mechanics.

In MRI, they apply the light pulse whose energy (= frequency × ℏ ) is almost equal to the energy difference between up and down (= 2 × ) nuclear spin magnetic moment (= μ_p = experimental value with No quantum mechanical prediction ) × external magnetic field (= B ) = 2 × μ_pB ( this-lower,  this-p.18-3.17 ) which is equal to the energy equation using geomagnetic ratio (= γ,  this-p.3-upper, p.7-upper,  this ).

This Resonance says  -- Classical magnetic energy in MRI
"This promotes the nuclei from low energy spin (parallel) to high energy spin (antiparallel) thus absorbing energy - excitation. The frequency (= ν or ω of this ) required to make this happen is specific to the difference in energy between the 'parallel' and 'antiparallel"

↑ As a result, MRI does Not need quantum mechanics at all, as seen in transistors.

MRI depends on NMR (= nuclear magnetic resonance ) discovered by Rabi's team relying on experimental values of nuclear magnetic moments irrelevant to quantum mechanical prediction

MRI technology is based on NMR (= nuclear magnetic resonance ) discovered by Rabi.

Rabi and several researchers relied on experimentally-measured values of nuclear magnetic moments (and classical mechanics) that can Not be predicted by (useless) quantum mechanics.

This-Rabi paper ↓

p.2-left-3rd-paragraph says  -- NMR = classical mechanics
"The process by which the precision frequency ν is measured has a rather close analog in classical mechanics."

p.7-left-4th-paragraph says  -- Experimental observation needed
"Since the values of the magnetic moment of any nucleus is calculated from an observed magnetic field and an observed frequency.."

↑ MRI, NMR are based on experimental observation of nuclear magnetic moments irrelevant to quantum mechanical prediction.

Neither quantum mechanics nor quantum chromodynamics (= QCD ) can predict nuclear spin magnetic moments nor hyperfine energy.

Quantum mechanics can Not predict proton's or nuclear spin magnetic moment that must be obtained from experimental results.

Nuclear spin magnetic moment (= magnetic field generated by nuclear spin ) is expressed as a tiny hyperfine energy level splitting between magnetic energies between nuclear spin and electron's orbits.

↑ Quantum mechanics cannot predict any energy levels or orbits of multi-electron atoms due to unsolvable Schrödinger equation.

↑ Quantum mechanical inability to predict any atomic energy levels means quantum mechanics also cannot predict hyperfine energy levels nor nuclear spin magnetic moment.

This-p.5-right-4th-paragraph says  -- Choose free parameters
"The effective nuclear charge Z, has been found empirically (= Not quantum mechanical theoretical prediction ) to be approximately equal to Z for s electrons"

This-p.2-left-3rd-last-paragraph says  -- No quantum prediction
"we use the core-Hartree (CH) potential and the Kohn-Sham (KS) potential derived within density-functional theory (= DFT )"  ← DFT with artificially-chosen exchange potential functionals cannot predict any energy values.

QCD cannot predict nuclear nor proton spin.

The present physics still cannot identify what objects generate proton's spin, which is called "proton spin crisis".

Quantum mechanics and quantum electrodynamics (= QED ) are known to be unable to predict any nuclear-related values such as nuclear spin magnetic moment.

So physicists rely on ad-hoc quantum chromodynamics (= QCD ) that just fit freely-adjustable parameters without analytical solution nor prediction.

What causes proton (= nuclear ) spin magnetic moment is uncertain (= called proton spin crisis ), which are free parameters that can Not predicted by QCD nor quantum mechanics

This site ↓

p.2(or p.1)-3rd-paragraph says  -- Uncertain proton spin
"Since the remaining fifty percent spin of the proton is still missing it is known as the proton spin crisis"

p.3(or p.2)-5th-paragraph says  -- No analytical solution of spin
" However, the analytical solution of the non-perturbative QCD is not known yet"

This-p.16-right-1~2nd-paragraphs say  -- Free parameters
"estimates of fitting systematic uncertainties in the extraction of the magnetic moments and polarizabilities resulting from the choice of fit form"

This-p.1-left-1st-paragraph says  -- Spin = free chosen parameters
"This makes the process of performing large, correlated fits a balancing act, with many choices and compromises to be made"

Atomic clocks use cesium's hyperfine energy (= frequency ) related to nuclear spin's direction to define the exact time, which does Not need quantum mechanics.

(Fig.2)  In atomic clocks, only cesium atoms which are excited to slightly upper hyperfine energy levels by microwave (= whose energy or frequency is used for defining the time ) are collected and detected under magnetic field.

Atomic clocks do Not use quantum mechanics.

Atomic clocks use only classical nuclear spin's energy levels' difference detectable by microwave (= whose frequency is used to define the exact time ) in cesium atoms, which does Not need quantum mechanics.

It is often said that atomic clocks in GPS (= which does Not use Einstein relativity ) needed quantum mechanics, which is untrue.

In atomic clocks, only cesium atoms which are excited to the upper hyperfine energy levels (= flipping classical nuclear spin magnetic moment ) by microwave pulse with some energy or frequency are deflected, collected and detected under magnetic field.

↑ When the number of these cesium atoms with the excited hyperfine state reaches a peak, the frequency of the microwave is used to define the exact standard of the time or the second for atomic clocks ( this-How does it all work? ).

This-3rd~4th-paragraphs say  -- No quantum mechanics
"When a cesium atom receives microwave energy at exactly the right frequency, it changes its energy state."

"At the far end of the tube, another magnetic field separates out the atoms that have changed their energy state if the microwave field was at exactly the correct frequency.... This locked frequency is then divided by 9,192,631,770 to give the familiar one pulse per second required by the real world."

↑ As I said, quantum mechanics can Not predict nuclear spin nor hyperfine energy.

So quantum mechanics is completely useless and irrelevant to atomic clocks.

Atomic clock inventors didn't use quantum mechanics.

Inventors of cecium atomic clocks used experimentally-observed cecium's energy levels which cannot be predicted by quantum mechanics.

Inventors of cecium atomic clocks (= Essen ) used exprimentally-observed cecium atomic energy instead of using quantum mechanics that cannot predict any atomic energies.

This-p.1-right~p.2 shows Essen and his team members determined cecium's frequency (= ν_E, ν_U ) from actual experimental obervation (= No quantum mechanics was used in this research ).

Futhermore, this atomic clock inventor criticized Einstein relativistic time dilation as unrealistic.

All quantum sensors do Not use quantum mechanics.

Quantum magnetic sensors, SQUID, nitrogen-vacancy centers in diamond do Not use quantum mechanics.

Quantum mechanics is completely useless in MRI, atomic clocks, all quantum sensors such as SQUID magnetic sensors, nitrogen-vacancy centers in diamond.

Feel free to link to this site.