Completing Canonical Quantization
-
Upload
allegra-moses -
Category
Documents
-
view
56 -
download
7
description
Transcript of Completing Canonical Quantization
2
Something Strange
L. Landau, E.M. Lifshitz, Quantum mechanics: Non-relativistic theory, 3rd ed., Pergamon Press, 1977.
"Thus quantum mechanics occupies a very unusual place among physical theories: it contains classical mechanics as a limiting case, yet at the same time it requires this limiting case for its own formulation."
6
List of Topics
1 Classical/Quantum connection
“Enhanced Quantization”
Canonical & Affine quantization Enhanced classical theories
2 Two toy models
3 Rotationally symmetric models
7
TOPIC 1
• Classical & Quantum formalism• Canonical coherent states• Classical Quantum formalism• Canonical transformations• Cartesian coordinates• Affine vs. canonical variables• Affine quantization as canonical
quantization
8
Action Principle Formulations
H
R
(0)given )( :Solution
/ yields 0 :Variation
})(]/[)({ :action Quantum
)0( ),0(given )( ),( :Solution
/ ,/ :yields 0 :Variation
))](),(()()([ :action Classical
2
t
tiA
dtttitA
qptqtp
qHppHqA
dttqtpHtqtpA
Q
Q
ccC
cC
H
H
VERY DIFFERENT
9
Restricted Action Principle
H
H
H
EE
E
E
E
EE
E
EEE
E
subsett
subspacet
t
tttiA
ttt
dtttitA
Q
Q
:})({ of Nature (2)
:})({ of Nature (1)
(0)given )( :Solution
] [
])( /)([ yields 0 :Variation
])( [ )()( :nsrestrictio Possible
})(]/[)({ :action Quantum
HH
H
H
(Gaussians)
(half space)
10
Unification of Classical and Quantum (1)
HS
)( )( : variationRestricted
)(]/[)( :action Quantum
tt
dtttitAQ
H
)(xx )(; qxqx
?
Macroscopic variations of Microscopic states:
Basic state: Translated basic state: Translated Fourier state: Coherent states:
)(~; pkpk )(, /)( qxeqpx qxip
00)( ; 0 ; , // iPQeeqp ipQiqP s.a.
11
Unification of Classical and Quantum (2)
dttqtpHtqtpA
dttqtptitqtpA
tqtpt
dtttitA
R
R
Q
))](),(()()([
)(),(]/[)(),( :action New
)(),()( : variationRestricted
)(]/[)( :action Quantum
H
H
CLASSICAL MECHANICS IS QUANTUM MECHANICS RESTRICTED TO A CERTAIN TWO DIMENSIONAL SURFACE IN HILBERT SPACE
subset
12
Canonical Transformations
dtqpHqpGqp
dtqpQPtiqpA
qpqpqqppqp
qpGdqdpdqp
dtqpHqp
dtqpQPtiqpA
R
R
)]~,~(~)~,~(~~~[
~,~)],(/[~,~
:action quantum Restricted
~,~)~,~(),~,~( ,
)~,~(~~~ :ations transformCanonical
)],([
,)],(/[,
:action quantum Restricted
H
H
13
Cartesian Coordinates
!ntization onical quational cant to tradi Equivalen
dqdpqpdqpqpd
eD
qqpQqppqpPqp
QP
qpqpqQpP
qpQPqpqpH
iR
]|,,|||,||[2
] min[ :metricStudy -Fubini
,, ; ,,
] 000 , 000 [ :meaning Physical
),;(),(0),(0
,),(,),(
:connection QuantumClassical/
2222
22
OHH
H
14
Quantum/Classical Summary
qqpHppqpHq
dttqtpHtqtp
dttqtpQPtitqtpA
eetqtpt
tQPtti
dttQPtitA
restQ
QtipPtiq
Q
/),( , /),(
))](),(()()([
)(),()],(/[)(),(
0)(),()(
:action quantum Restricted
)(),(/)(
)()],(/[)(
:action Qauntum
.
/)(/)(
H
H
H
15
Is There More?
• Are there other two-dimensional sheets of normalized Hilbert space vectors that may be used in restricting the quantum action and which lead to an enhanced classical canonical formalism?
16
Is There More?
• Are there other two-dimensional sheets of normalized Hilbert space vectors that may be used in restricting the quantum action and which lead to an enhanced classical canonical formalism?
YES !
17
Affine Variables
)/~
2/11/(2/,,
:unity of Resolution
]}~
/)'(''//'[{,','
:function Overlap
0]~/)1[(; ,
)0 ; 0( :statescoherent Affine
2/)( ; ],[],[],[
},{},{},{ : variablesAffine
/~221
/)ln(/
dqdpqpqpI
ppqqiqqqqqpqp
iDQeeqp
QPPQDDQQPQPQQQi
dqpqqpqqq
DqiipQ
[(
also (q < 0 , Q < 0) U (q > 0 , Q > 0)
s.a.
18
Affine Quantization (1)
))](~),(~(~))(~),(~('~)(~)(~[
)(~),(~)],(/[)(~),(~
,~,~ :ation transformCanonical
))](),(()()([
)(),()],(/[)(),(
)(),()( :action Restricted
)()],(/[)(
:action Quantum
dttqtpHtqtpGtptq
dttqtpQDtitqtpA
qpqp
dttqtpHtptq
dttqtpQDtitqtpA
tqtpt
dttQDtitA
R
R
Q
H'
H'
H'
subset
19
Affine Quantization (2)
2
2222122
/~
, :Cartesian becomes Metric
~~]|, ,|||,||[2
:metricStudy -Fubini
,, ; ,,
] 1 , 0 [ :meaning Physical
),;(),(),(
,),(,),('
:connection QuantumClassical/
dqqdpqqpdqpqpd
qqpQqppqqpDqp
QD
qpqpqqQpqQD
qpQDqpqpqH
OH'H'
H'
20
The Q/C Connection : Summary
• The classical action arises by a restriction of the quantum action to coherent states
• Canonical quantization uses P and Q which must be self adjoint
• Affine quantization uses D and Q which are self adjoint when Q > 0 (and/or Q < 0)
• Both canonical AND affine quantum versions are consistent with classical, canonical phase space variables p and q
• Now for some applications!
21
TOPIC 2
• Solutions of the first model have singularities
• Canonical quantum corrections• Affine quantum corrections• Affine quantization resolves singularities!• A second classical model is similar
200
100
2
02
)1()( , )1()(
)()(
0)( , ])()()()([
tpqtqtpptp
tptp
tqdttptqtptqA TC
22
Toy Model - 1
qQQeeqQQee
EMECKDDQC
KtMtqKt
ttp
qCqpqpDDQqp
taaEtqtaatp
aqaqpqpPQPqp
tpqtqtpptp
qdtqppqA
DqiDqiiqPiqP
C
/)ln(/)ln(//
020
212
22
221
220
222
200
100
2
;
4 ; 4/ ;
0])[()( , )(
)()( :Solution
/,, :quant. Affine
))(sin()/()( , ))(cot()( :Solution
2/ ; ,, :quant. Canonical
)1()( , )1()( :Solution
0 ; ][ :action. Classical
23
Toy Model - 2
)( )/('
' ; |Q|/
/'||/,||/, :Model
)||,||/(,),(,),(
)],([,)],(/[,
])( ; 0 [ :action classical Extended
][ ; |)]|/([ :modelToy
0|| ,0|| ; , :statescoherent Affine
)( , ],[],[ :onquantizati Affine
22
2122122
222122
21
2221
/|)ln(|/
21
CsBohr radiuCmeC
PCeeC
qCqCpqpQePqp
QqpqPqpQPqpqpH
dtqpHpqdtqpQPtiqpA
abDaQ
dtqeppqA
qQeeqp
PQQPDDQQiQPQ
mm
mm
R
mC
DqiipQ
HH
H
24
Enhanced Toy Models : Summary
• Classical toy models exhibit singular solutions for all positive energies
• Enhanced classical theory with canonical quantum corrections still exhibits singularities
• Enhanced classical theory with affine quantum corrections removes all singularities
• Enhanced quantization can eliminate singularities
25
TOPIC 3
• Rotationally symmetric models
• Free quantum models for • Interacting quantum models for
• Reducible operator representation is the key
,) ,,(,),(
,,),(
}{ , )(][),( 122
022
02
21
qpQPqpqpH
qpqpqpH
N
N
ppqqmpqpH Nnn
H
H
][ 2 ppp
. .
.
26
Rotationally Sym. Models (1)
NthatnecessaryisitNWhen
NQQmP
iPQQqPp
YXZqpLE
qZqpYpX
RNOqOqpOp
NqqmpqpH
qqqppp
jkkj
NN
/,
,:)(::::nHamiltonia
],[;, :onQuantizati
)(, :motion of Constants
,, :invariants Basic
),(;,under Invariant
;)(][),(
),...,(,),...,( :scoordinate space Phase
0
220
220
221
222
22
220
220
221
11
H
O
27
Rotationally Sym. Models (2)
; )( :Result
m)2/1()( :Uniqueness
]1)([ ; )(
)(
)sin()(
)()(
ondistributi state ground theofon ansformatiFourier tr
).()( : with )(
real aith equation wer Schroeding
m4/
002/
212)2(2/
2212/)cos(
2/
2
2
222
p
bp
NN
NNrp
N
NNN
Nipr
Nxpi
N
NNN
epC
bbf
dbbfdbbfe
ddrrreK
dddrrre
xdxepC
xr symmetryrotationalfullx
und stateunique gro
A free theory!
29
Rotationally Sym. Models (3)
Nqqmp
qmvqmqmp
qpQSmRvQSmR
SQmPqpqpqp
PqQpiqp
RiQSmPiSQm
Nqmpwqmp
qpQmPwQmPqpqpqp
PqQpiqpPiQm
;)()(
)()(
;,:}])([::)(:
:)(:{;,;,;,
;0]/)(exp[;,
10;0;0])([;0])([
;)()(
,:})(:::{,,~,
0]/)(exp[, ; 00)(
220
220
221
224422221222
21
222222221
22221
2220
2220
221
2220
2220
221
0
H'
HTEST
REAL
30
Rot. Sym. Models : Summary• Conventional quantization works if N is
finite but leads to triviality if N is infinite• Enhanced quantization applies even for
reducible operator representations• Using the Weak Correspondence
Principle a nontrivial quantization results if N is finite
or N is infinite --- with NO divergences !• Class. & Quant. formalism is similar for all N
qpqpqpH
,,),( H
WHAT HAS BEEN ACCOMPLISHED ??
31
• Canonical quantization requires Cartesian coordinates, but WHY is not clear
• Canonical quantization works well for certain problems, but NOT for all problems
• Enhanced quantization clarifies coordinate transformations and Cartesian coordinates
• Enhanced quantization can yield canonical results -- OR provide proper results when canonical quantization fails
Canonical vs. Enhanced
32
Other Enh. Quant. Projects
• Simple models of affine quantization eliminating classical singularities (on going)
• Covariant scalar models (done)• Affine quantum gravity (started)• Incorporating constrained systems within
enhanced quantization (started)• Additional sheets of vectors in Hilbert space
relating quan. and class. models (started)• Extension to fermion fields (hints)
4n
35
References
• ``Enhanced Quantization: A Primer'', J. Phys. A: Math. Theor. 45, 285304
(8pp) (2012); arXiv:1204.2870• ``Enhanced Quantization on the Circle’’; Phys.
Scr. 87 035006 (5pp) (2013); arXiv:1206.1180• ``Enhanced Quantum Procedures that
Resolve Difficult Problems’’; arXiv: 1206.4017• ``Revisiting Canonical Quantization’’; arXiv:
1211.735