Physics/Essays/Fedosin/Quantum Electromagnetic Resonator

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Quantum Electromagnetic Resonator (QER) – a closed topological object of three dimensional space, in the general case – is a ‘’cavity’’ of arbitrary form, which has definite ‘’surface’’ and ‘’thickness’’. The QER has “infinite” phase shifted oscillations of electromagnetic field, due to its quantum properties.

History

It has happened, that such physical values as capacitance and inductance have no interest in the modern quantum electrodynamics. Furthermore, they are neglected even in classical electrodynamics, where electric and magnetic fields are dominated. The point is that, the last are not included in evident form in the Maxwell's equations, and so the resulting solutions includes fields only. Yes, sometimes these coefficients were obtained from the solutions of Maxwell equations, but it was very rarely.

It is known too, that field approach in electrodynamics that considered point charges leads to the “fool infinities”, as the interaction radius tends to zero. Furthermore, these infinities are presented in quantum electrodynamics too, where power methods are developed to compensate them.

Contrary to theoretical physics, applied physics has widely used reactive parameters, such as capacitance and inductance, firstly in electrotechnics and then in applied radiotechnics. Now reactive parameters are widely used in information technologies, which are based on the generation, transmission and radiation of electromagnetic waves of different frequencies.

The present day situation (without proper development of the theory of reactive parameters such as inductance, capacitance and electromagnetic resonator) prevents or slows developments in information technology and quantum computing. Note that, mechanical harmonic oscillator was considered in quantum mechanics in the early fourth decade of the twentieth century, when quantum theory was developed. However, quantum consideration of the LC  circuit was started only by Louisell (1973). [1]

Since then, there have been no practical examples of quantum capacitance and inductance, so this approach did not obtain proper consideration.

A theoretically correct introduction of quantum capacitance, based on the density of states, first was presented by Luryi (1988) [2] for QHE.

However, Luryi did not introduce quantum inductance, and this approach was not considered in quantum LC circuits and resonators. A year later, Yakymakha (1989) [3] considered an example of series and parallel quantum LC  circuits (characteristic impedances) during QHE explanation (integer and fractional). However this work did not consider the Schrodinger equation for the quantum LC circuit.

For the first time, both quantum values, capacitance and inductance, were considered by Yakymakha (1994), [4] during spectroscopic investigations of MOSFETs at the very low frequencies (sound range). The flat quantum capacitances and inductances here had thicknesses about the Compton wave length of an electron, and its characteristic impedance – the wave impedance of free space.

And three year later, Devoret (1997) [5] presented a complete theory of the Quantum LC circuit (applied to the Josephson junction). Possible application of the quantum LC circuits and resonators in the quantum computation are considered by Devoret (2004). [6]

Classical electromagnetic resonator

In the general case, a classical electromagnetic resonator (CER) is a cavity resonator. It is a hollow closed conductor such as a metal box or a cavity within a metal block, containing electromagnetic waves reflecting back and forth between the cavity's walls. Therefore, a CER has infinite resonance frequencies, due to the three dimensions. For example, the rectangular CER has the following resonance frequencies:

ωmnp=1ε0εrμ0μr(mπa)2+(nπb)2+(pπl)2, 

where m,n,p=integer. ; a,b,l  are the width, thickness and length correspondingly, ε0  is the electric constant, εr  is the relative permittivity, μ0  is the vacuum permeability, μr  is the relative permeability.

Contrary to the classical LC circuit, both electric and magnetic fields are displaced in the same volume of CER.

These oscillating electromagnetic fields, in the classical case, are like standing waves, that form electromagnetic waves, that could be radiated to the external world.

Now CERs are widely used in the radio frequency range (centimetre and decimetre diapason). Furthermore, they are also used in quantum electronics, which deal with monochromic light waves.

Quantum general approach

Quantum LC circuit oscillator

In classical physics we have the following correspondence between mechanical and electrodynamical physical parameters:

Magnetic inductance and mechanical mass:

Lm ;

Electric capacitance and reciprocal elasticity:

C1/k ;

Electric charge and coordinate displacement:

qx .

The inductance momentum quantum operator in the electric charge space can be presented in the following form:

p^Lq=iddq,p^Lq*=iddq,(1a) 

where   is the reduced Planck constant, p^L*  is the complex-conjugate momentum operator.

The capacitance momentum quantum operator in magnetic charge space can be presented in the following form:

p^Cϕ=iddϕ,p^Cϕ*=iddϕ,(1b) 

where ϕ  is the induced magnetic flux.

Considering that there is no free magnetic flux, but it could be imitated by electric current (i ):

ϕ=Li, 

we may introduce the third momentum quantum operator in the current form:

p^Ci=iLddi,p^Ci*=iLddi,(1c) 

These quantum momentum operators define three Hamilton operators:

H^Lq=22Ld2dq2+Lω022q^2(2a) 
H^Cϕ=22Cd2dϕ2+Cω022ϕ^2(2b) 
H^Ci=2ω022Ld2di2+Lω02i^2,(2c) 

where ω0=1LC  is the resonance frequency.

We consider the case without dissipation (R=0 ).

The only difference of the charge spaces and current spaces here from the traditional 3D- coordinate space is that they are one dimensional (1D).

The Schrodinger equation for the quantum LC circuit may be defined in three forms:

22Ld2Ψdq2+Lω022q2Ψ=WΨ(3a) 
22Cd2Ψdϕ2+Cω022ϕ2Ψ=WΨ(3b) 
2ω022Ld2Ψdi2+Lω02i2Ψ=WΨ.(3c) 

To solve these equations we introduce the following dimensionless variables:

ξq=qq0;q0=Lω0;λq=2Wω0(4a) 
ξϕ=ϕϕ0;ϕ0=Cω0;λϕ=2Wω0(4a) 
ξi=ii0;i0=ω0L;λi=2Wω0.(4a) 

where q0  is scaling induced electric charge; ϕ0  is scaling induced magnetic flux and i0  is scaling induced electric current.

Then the Schrodinger equation will take the form of the differential Chebyshev-Ermidt equation:

(d2dξ2+λξ2)Ψ=0. 

The eigenvalues of the Hamiltonian will be:

Wn=ω0(n+1/2), 

where at n=0  we shall have zero oscillation:

W0=ω0/2. 

In the general case the scaling charge and flux can be rewritten in the form:

q0=Lω0=e4πα 
ϕ0=Cω0=απhe, 

where α  is the fine structure constant.

Furthermore, the scaling current and voltage will be here:

I0=ϕ0L=παecλ0 
V0=q0C=4παcheλ0, 

where λ0=hm0c is the particle wavelength.

These scaling parameters were obtained by using the following quantum resonator parameters:

Z0=2αRK(5a) 

for characteristic impedance, and

ω0=2πcλ0(5b) 

for resonance frequency, and RK=he2  is the von Klitzing constant. With this we have: L=μ0λ02π,  C=ε0λ02π. 

These three equations (3) form the base of a nonrelativistic quantum electrodynamics, which considers elementary particles from an intrinsic point of view. Standard quantum electrodynamics considers elementary particles from an external point of view.

Resonator as quantum LC circuit

The Luryi density of states (DOS) approach defines quantum capacitance as:

CQR=qR2D2DSR, 

and quantum inductance as:

LQR=ϕR2D2DSR, 

where SR  is the resonator surface area, D2D=mπ2  is two dimensional (2D) DOS, qR  is the induced electric charge, and ϕR  is the induced magnetic flux. Note that these charges should be defined afterward.

The energy stored on quantum capacitance:

WCR=qR22CQR=12D2DSR. 

The energy stored on quantum inductance:

WLR=ϕR22LQR=12D2DSR=WCR. 

The resonator angular frequency is:

ωQR=1LQRCQR=1qRϕRD2DSR. 

The energy conservation law for zero oscillation:

WQR=12ωQR=2qRϕRD2DSR=WCR=WLR. 

This equation can be rewritten as:

qRϕR=, 

from which it is evident that induced charge qR  and induced magnetic flux ϕR  are connected to electric and magnetic fluxes in the resonator.

The characteristic resonator impedance is:

ZQR=LQRCQR=ϕRqR={ϕ0e=RK,for Quantum Hall Effect 2αϕ0e=2αRK=Z0,for other  

where ϕ0=h/e  is the magnetic flux quantum, Z0=2αh/e2=μ0c=1ε0c=μ0ε0 is the impedance of free space.

Considering the above equations, we have the following electric and magnetic sets of fluxes:

qR={qR1=e2π,for Quantum Hall Effect qR2=e4πα,for other  
ϕR={ϕR1=ϕ02π,for Quantum Hall Effect ϕR2=ϕ04πβ,for other  

where β=ϕ022μ0hc=14α  is the magnetic coupling constant.

These values are not the real charge and magnetic flux, but maximal quantities that maintain the energy balance between resonator oscillation energy and total energy on capacitance and inductance:

ωQR=WQL(t)+WQC(t). 

Since the capacitance oscillations are phase shifted (ψ=π/2 ) with respect to inductance oscillations, we get:

WQL={0,at t=0;ψ=0 andt=TQR2;ψ=πWQL,at t=TQR4;ψ=π4 andt=3TQR4;ψ=3π4 
WQC={WQC,at t=0;ψ=0 andt=TQR2;ψ=π0,at t=TQR4;ψ=π4 andt=3TQR4;ψ=3π4 

where TQR=2πωQR  is the oscillation period.

De Broglie electromagnetic resonator

De Broglie matter wave [7] can be considered for the electric charge and magnetic flux. Actually, using the de Broglie approach in the form of Blohintzev [8] we can derive the following properties of charge quantum resonator (de Broglie charge bubble).

De Broglie electric charge

The electric charge in the de Broglie wave approach can be presented by the following wave function:

Ψ(qE,t)=AEexp[i(ϕMqEWLt)]=AEexp[i(γE)] 

with

WL=ωL 
ϕM=kE, 

where kE=2πqλ is electric charge "wave vector" and qλ is electric charge "wave length". The phase function

γE=kEqEωLt 

has differential

dγE=kEdqEωLdt=0. 

So, the phase current is:

iph=dqEdt=ωLkE 

Considering wave energy in the form

WL=ϕM22L=2kE22L=ωL, 

where L  is de Broglie quantum inductance, and frequency

ωL=kE22L 

de Broglie "group current" will be:

ig=dωLdkE=kEL. 

On the other hand, we have a limit for the group current:

ig=ecλ. 

Equating group currents, we may derive the de Broglie quantum inductance:

L=heqλλc. 

De Broglie magnetic flux

Magnetic flux in the de Broglie wave approach can be presented by the following wave function:

Ψ(qM,t)=AMexp[i(ϕEqMWCt)]=AMexp[i(γM)] 

with

WC=ωC 
ϕE=kM, 

where qM is the space coordinate, kM=2πqMλ is magnetic flux "wave vector" and qMλ is magnetic flux "wave length". The phase function

γM=kMqMωCt 

has differential

dγM=kMdqMωCdt=0. 

The phase voltage will be:

vph=dqMdt=ωCkM 

Considering the wave energy in the form

WC=ϕE22C=2kM22C=ωC, 

where C  is de Broglie quantum cdpacitance, and frequency

ωC=kM22C 

the de Broglie "group voltage" will be:

vg=dωCdkM=kMC. 

On the other hand we have the following limit for the group voltage:

vg=hce1λ. 

Equating group voltages, we may derive de Broglie capacitance:

C=eqMλλc. 

De Broglie LC circuit

Using separated electric and magnetic de Broglie charge approaches, we should consider the pilot wave approach to maintain electric and magnetic charges in a stable form. However, when we consider the composite de Broglie wave function in the following form:

Ψ(qM,t)=AMAEexp[i(ϕMqEWLt)]exp[i(ϕEqMWCt)] 

with

WC=ωC=WL=ωL 
ϕE=kM, 
ϕM=kE, 

then separated electric charge and magnetic flux produce a composite quantum resonator.

Considering that the de Broglie particle should be consistent with the quantum resonator, we determine the electric charge and magnetic flux induced in the LC circuit:

qλ=γqe 
qMλ=γϕhe. 

The reactive parameters in that case will be:

L(λ)=RKγqλc 
C(λ)=1γϕRKλc. 

Characteristic impedance for the de Broglie charged particle resonator:

Zλ=L(λ)C(λ)=RKγϕγq=2αRK. 

Resonance frequency for the de Broglie charged particle resonator:

ω(λ)=1L(λ)C(λ)=cλγϕγq=2πcλ. 

Thus, we have the following algebraic system for unknown parameters:

γϕγq=2π 
γϕγq=2α. 

The solution of this system is as follows:

γq=παγϕ=4πα 

Then, induced electric charge and magnetic flux may be rewritten as:

qλ=γqe =παe 
qMλ=γϕhe=4παhe, 

and reactive parameters are:

L(λ)=αRKπλc 
C(λ)=14παRKλc. 

So, quantum oscillations of electric charge and magnetic flux make the charged de Broglie bubble stable in time.

Applications

Bohr atomic resonator

General information on Bohr atom. Bohr radius is:

aB=λ02πα, 

where α  is the electric fine structure constant, λ0  is the Compton wavelength of electron.

Bohr surface scaling parameter for electron disc is:

SB=2πaB2. 

Bohr angular frequency is:

ωB=maB2, 

where   is reduced Plank constant and m  is electron mass.

Bohr density of states is:

DB=1ωBSB=m2π2. 

Standard DOS quantum resonator approach yields the following values for the Bohr atom reactive quantum parameters:

CQRB=qR22DBSB=e24παm2π2SB=ε0λ0SB 
LQRB=ϕR22DBSB=ϕ024πβm2π2SB=μ0λ0SB, 

where ϕ0=h/e  is the magnetic flux quantum, β=ϕ022μ0hc=14α  is the magnetic coupling constant.

Thus, s.c. "Bohr atom" could be considered as discoid quantum resonator which has radius aB  and thickness λ0 .

Electron resonator

Let suppose that the electron has its mass defined by the quantum oscillations, more precisely by the oscillations of the quantum LC circuit:

ωe=mec2. 

The oscillation length will be:

xe=λ02π, 

where λ0=hmec  is the Compton wavelength of the electron.

Further, let us consider that the mass me  is uniformly distributed on the electron surface:

Se=2πxe2=λ022π. 

Electron angular frequency is:

ωe=mec2=2πcλ0, 

where c  is the speed of light.

Then we can find out the density of states for this mass:

De=1Se1mec2=me2π2. 

Standard DOS quantum resonator approach yields the following values for the electron reactive quantum parameters:

CQRe=qR22DeSe=e24παme2π2Se=ε0λ0Se=ε0λ02π. 
LQRe=ϕR22DeSe=ϕ024πβme2π2Se=μ0λ0Se=μ0λ02π. 

Thus, s.c. "free electron" could be considered as discoid quantum resonator which has radius xe .

Photon resonator

As it is known, the photon momentum is defined as:

pp=Wpc, 

where c  is the speed of light, Wp=ωp  is the energy of a photon.

So, the "effective (energy) photon mass" could be defined as:

mp=ωpc2. 

Then the length scaling parameter of harmonic oscillator will be:

xp=mpωp=λp2π, 

where λp=2πcωp  is the photon wavelength.

Photon surface scaling parameter is:

Sp=4πxp2=λp2π. 

Photon angular frequency is:

ωp=2πcλp. 

Photon density of states is:

Dp=1SpWp=πλphc. 

Standard DOS quantum resonator approach yields the following values for the photon reactive quantum parameters:

CQRp=qp2DpSp=e24παπλphcSp=ε02λpSp=ε0λp2π, 
LQRp=ϕp2DpSp=ϕ024πβπλphcSp=μ02λpSp=μ0λp2π. 

Thus, photon can be considered as quantum resonator which has radius xp .

Quantum Hall resonator

General information on the Hall resonator. Cyclotron frequency is:

ωc=eBm, 

where e  is the elementary charge, B  is the magnetic field induction and m  is the electron effective mass in solid.

Magnetic length is:

lB=eB, 

Scaling area parameter is:

SH=2πlB2=heB=1nH, 

where nH  is the electron surface density.

Density of states is:

DH=nHωc=m2π2. 

Density of states quantum capacitance is:

CH=qH2DHSH=e24πm2π2SH=αε0λ0SH 

or in another form:

CH=ε0dCSH, 

where dC=λ0α  is the capacitance thickness.

Density of states quantum inductance is:

LH=ϕH2DHSH=ϕ024πm2π2SH=βμ0λ0SH 

or in another form:

LH=μ0dLSH, 

where dL=λ0β=4αλ0  is the inductance thickness.

Thus, quantum Hall resonator has the cylindrical form with radius lB  and two different thickness: dC  for capacitance and dL  for inductance.

Flat atom resonator

A very low frequency resonance was discovered by Yakymakha (1994) [4] with mesoscopic parameters:

the angular frequency: ω0=1L0C0=5088  rad/s,

the surface scaling parameter: S0=hmω0=1.4196107  m2 ,

the quantum capacitance: C0=1ω0Z0=5.1805107  F, where Z0  is the impedance of free space,

the quantum inductance: L0=Z0ω0=7.3524102  H.

In the case of quantum resonator DOS will be:

D0=1ω0S0=m2π2. 

Quantum resonator capacitance is:

CQR0=qR22D0S0=ε0λ0S0, 

where λ0=hm0c .

Quantum resonator inductance is:

LQR0=ϕR22D0S0=μ0λ0S0. 

Note that, even in the mesoscopic case we have the reactive parameter thickness about Compton wave length of electron.

See also

References

Template:Reflist

Reference books

  • Stratton J.A.(1941). Electromagnetic Theory. New York, London: McGraw-Hill.p.615. djvu
  • Детлаф А.А., Яворский Б.М., Милковская Л.Б.(1977). Курс физики. Том 2. Электричество и магнетизм (4-е издание). М.: Высшая школа, "Reference Book on Electricity" djvu
  • Гольдштейн Л.Д., Зернов Н.В. (1971). Электромагнитные поля. 2- издание. Москва: Советское Радио. 664с. "Electromagnetic Fields" djvu
  1. Louisell W. H. (1973). “Quantum Statistical Properties of Radiation”. Wiley, New York.
  2. Serge Luryi (1988). "Quantum capacitance device". Appl.Phys.Lett. 52(6). Pdf
  3. Yakymakha O.L.(1989). High Temperature Quantum Galvanomagnetic Effects in the Two- Dimensional Inversion Layers of MOSFET's (In Russian). Kyiv: Vyscha Shkola. p.91. Template:ISBN. djvu.
  4. 4.0 4.1 Yakymakha O.L., Kalnibolotskij Y.M. (1994). "Very-low-frequency resonance of MOSFET amplifier parameters". Solid- State Electronics 37(10),1739-1751 Pdf.
  5. Deboret M.H. (1997). "Quantum Fluctuations". Amsterdam, Netherlands: Elsevier. pp.351-386. Pdf.
  6. Devoret M.H., Martinis J.M. (2004). "Implementing Qubits with Superconducting Integrated Circuits". Quantum Information Processing, v.3, N1. Pdf
  7. Louis de Broglie. The wave nature of the electron, Nobel Lecture, 12, 1929 PDF
  8. Блохинцев Д. И. Основы квантовой механики.- М.:ГосИздат, 1949.-588с.