quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 ·...
TRANSCRIPT
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Quantum mechanicswithout particles
HARVARD
Institute Lecture,Indian Institute of Technology, Kanpur
January 21, 2014
sachdev.physics.harvard.eduTuesday, January 21, 14
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1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
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1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
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Principles of Quantum Mechanics: 1. Quantum Superposition
The double slit experiment
Interference of water wavesTuesday, January 21, 14
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The double slit experiment
Send electrons through the slits
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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The double slit experiment
Send electrons through the slits
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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The double slit experiment
Interference of electrons
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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The double slit experiment
Interference of electrons
Which slit does an electron
pass through ?
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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The double slit experiment
Interference of electrons
Which slit does an electron
pass through ?
No interference when you watch the electrons
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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The double slit experiment
Interference of electrons
Which slit does an electron
pass through ?
Each electron passes
through both slits !
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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Let |L� represent the statewith the electron in the left slit
|L�
The double slit experiment
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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And |R� represents the statewith the electron in the right slit
Let |L� represent the statewith the electron in the left slit
|L� |R�
The double slit experiment
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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And |R� represents the statewith the electron in the right slit
Let |L� represent the statewith the electron in the left slit
Actual state of the electron is|L� + |R�
|L� |R�
The double slit experiment
Principles of Quantum Mechanics: 1. Quantum Superposition
Tuesday, January 21, 14
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Quantum Entanglement: quantum superposition with more than one particle
Principles of Quantum Mechanics: 1I. Quantum Entanglement
Tuesday, January 21, 14
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Quantum Entanglement: quantum superposition with more than one particle
Principles of Quantum Mechanics: 1I. Quantum Entanglement
Hydrogen atom:
Tuesday, January 21, 14
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Quantum Entanglement: quantum superposition with more than one particle
Principles of Quantum Mechanics: 1I. Quantum Entanglement
Hydrogen atom:
=1⌃2
(|⇥⇤⌅ � |⇤⇥⌅)
Hydrogen molecule:
= _
Tuesday, January 21, 14
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Quantum Entanglement: quantum superposition with more than one particle
Principles of Quantum Mechanics: 1I. Quantum Entanglement
_
Tuesday, January 21, 14
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Quantum Entanglement: quantum superposition with more than one particle
Principles of Quantum Mechanics: 1I. Quantum Entanglement
_
Tuesday, January 21, 14
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Quantum Entanglement: quantum superposition with more than one particle
Principles of Quantum Mechanics: 1I. Quantum Entanglement
_
Tuesday, January 21, 14
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Quantum Entanglement: quantum superposition with more than one particle
Principles of Quantum Mechanics: 1I. Quantum Entanglement
_
Einstein-Podolsky-Rosen “paradox”: Non-local correlations between observations arbitrarily far apart
Tuesday, January 21, 14
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1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
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1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
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E
MetalMetal
carryinga current
InsulatorSuperconductor
k
E
MetalMetal
carryinga current
InsulatorSuperconductor
k
Sommerfeld-Bloch theory of metals, insulators, and superconductors:many-electron quantum states are adiabatically
connected to independent electron states
Metals
Tuesday, January 21, 14
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E
MetalMetal
carryinga current
InsulatorSuperconductor
k
E
MetalMetal
carryinga current
InsulatorSuperconductor
k
Boltzmann-Landau theory of dynamics of metals:
Long-lived quasiparticles (and quasiholes) have weak interactions which can be described by a Boltzmann equation
Metals
Tuesday, January 21, 14
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1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
![Page 26: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/26.jpg)
1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
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Spinning electrons localized on a square lattice
H =�
�ij⇥
Jij⌅Si · ⌅Sj
J
J/�
Examine ground state as a function of �
S=1/2spins
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H =�
�ij⇥
Jij⌅Si · ⌅Sj
J
J/�
At large ground state is a “quantum paramagnet” with spins locked in valence bond singlets
=1⌅2
⇥���⇥⇤⌅�
��� ⇤⇥⌅⇤
�
Spinning electrons localized on a square lattice
Tuesday, January 21, 14
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H =�
�ij⇥
Jij⌅Si · ⌅Sj
J
J/�
=1⌅2
⇥���⇥⇤⌅�
��� ⇤⇥⌅⇤
Nearest-neighor spins are “entangled” with each other.
Can be separated into an Einstein-Podolsky-Rosen (EPR) pair.
Spinning electrons localized on a square lattice
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H =�
�ij⇥
Jij⌅Si · ⌅Sj
J
J/�
For � ⇡ 1, the ground state has antiferromagnetic (“Neel”) order,
and the spins align in a checkerboard pattern
Spinning electrons localized on a square lattice
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��c
=1⌅2
⇥���⇥⇤⌅�
��� ⇤⇥⌅⇤
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Pressure in TlCuCl3
��c
=1⌅2
⇥���⇥⇤⌅�
��� ⇤⇥⌅⇤
A. Oosawa, K. Kakurai, T. Osakabe, M. Nakamura, M. Takeda, and H. Tanaka, Journal of the Physical Society of Japan, 73, 1446 (2004).
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TlCuCl3
An insulator whose spin susceptibility vanishes exponentially as the temperature T tends to zero.
Tuesday, January 21, 14
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TlCuCl3
Quantum paramagnet at ambient pressure
Tuesday, January 21, 14
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TlCuCl3
Neel order under pressureA. Oosawa, K. Kakurai, T. Osakabe, M. Nakamura, M. Takeda, and H. Tanaka, Journal of the Physical Society of Japan, 73, 1446 (2004).
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��c
=1⌅2
⇥���⇥⇤⌅�
��� ⇤⇥⌅⇤
Tuesday, January 21, 14
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Quasiparticles in the paramagnetic phase
��cSpin S = 1“triplon”
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��cSpin S = 1“triplon”
Quasiparticles in the paramagnetic phase
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��cSpin S = 1“triplon”
Quasiparticles in the paramagnetic phase
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Quasiparticles in the Neel phase
��c
Spin waves
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��c
Spin waves
Quasiparticles in the Neel phase
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��c
Spin waves
Quasiparticles in the Neel phase
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Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya,
Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, 205701 (2008)
Excitations of TlCuCl3 with varying pressure
0 0.5 1 1.5 2 2.5 30
0.2
0.4
0.6
0.8
1
1.2
Pressure [kbar]
Ener
gy [m
eV]
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Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya,
Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, 205701 (2008)
0 0.5 1 1.5 2 2.5 30
0.2
0.4
0.6
0.8
1
1.2
Pressure [kbar]
Ener
gy [m
eV]
Excitations of TlCuCl3 with varying pressure
Triplon quasiparticles
of the
quantum paramagnet
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Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya,
Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, 205701 (2008)
0 0.5 1 1.5 2 2.5 30
0.2
0.4
0.6
0.8
1
1.2
Pressure [kbar]
Ener
gy [m
eV]
Excitations of TlCuCl3 with varying pressure
Spin waves above
the Neel state
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Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya,
Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, 205701 (2008)
0 0.5 1 1.5 2 2.5 30
0.2
0.4
0.6
0.8
1
1.2
Pressure [kbar]
Ener
gy [m
eV]
Excitations of TlCuCl3 with varying pressure
S. Sachdev, arXiv:0901.4103
Quasiparticle analogof the Higgs bosonat the theoreticallypredicted energy!
Tuesday, January 21, 14
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��c
=1⌅2
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��� ⇤⇥⌅⇤
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��c
A. W. Sandvik and D. J. Scalapino, Phys. Rev. Lett. 72, 2777 (1994).
Quantum critical point with non-local entanglement in spin wavefunction
=1⌅2
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��� ⇤⇥⌅⇤
Tuesday, January 21, 14
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• Long-range entanglement
• No quasiparticles - no simple description of excita-
tions.
• The low energy excitations are described by a theory
which has the same structure as Einstein’s theory
of special relativity, but with the spin-wave velocity
playing the role of the velocity of light.
• The theory of the critical point has an even larger
symmetry corresponding to conformal transforma-
tions of spacetime: we refer to such a theory as a
CFT3
Characteristics of quantum critical point
Tuesday, January 21, 14
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• Long-range entanglement
• No quasiparticles - no simple description of excita-
tions.
• The low energy excitations are described by a theory
which has the same structure as Einstein’s theory
of special relativity, but with the spin-wave velocity
playing the role of the velocity of light.
• The theory of the critical point has an even larger
symmetry corresponding to conformal transforma-
tions of spacetime: we refer to such a theory as a
CFT3
Characteristics of quantum critical point
Tuesday, January 21, 14
![Page 51: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/51.jpg)
• Long-range entanglement
• No quasiparticles - no simple description of excita-
tions.
• The low energy excitations are described by a theory
which has the same structure as Einstein’s theory
of special relativity, but with the spin-wave velocity
playing the role of the velocity of light.
• The theory of the critical point has an even larger
symmetry corresponding to conformal transforma-
tions of spacetime: we refer to such a theory as a
CFT3
Characteristics of quantum critical point
Tuesday, January 21, 14
![Page 52: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/52.jpg)
• Long-range entanglement
• No quasiparticles - no simple description of excita-
tions.
• The low energy excitations are described by a theory
which has the same structure as Einstein’s theory
of special relativity, but with the spin-wave velocity
playing the role of the velocity of light.
• The theory of the critical point has an even larger
symmetry corresponding to conformal transforma-
tions of spacetime: we refer to such a theory as a
CFT3
Characteristics of quantum critical point
Tuesday, January 21, 14
![Page 53: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/53.jpg)
1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
![Page 54: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/54.jpg)
1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
![Page 55: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/55.jpg)
• Allows unification of the standard model of particle
physics with gravity.
• Low-lying string modes correspond to gauge fields,
gravitons, quarks . . .
String theory
Tuesday, January 21, 14
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• A D-brane is a d-dimensional surface on which strings can end.
• The low-energy theory on a D-brane has no gravity, similar to
theories of entangled electrons of interest to us.
• In d = 2, we obtain strongly-interacting CFT3s. These are
“dual” to string theory on anti-de Sitter space: AdS4.
Tuesday, January 21, 14
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• A D-brane is a d-dimensional surface on which strings can end.
• The low-energy theory on a D-brane has no gravity, similar to
theories of entangled electrons of interest to us.
• In d = 2, we obtain strongly-interacting CFT3s. These are
“dual” to string theory on anti-de Sitter space: AdS4.
Tuesday, January 21, 14
![Page 58: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/58.jpg)
• A D-brane is a d-dimensional surface on which strings can end.
• The low-energy theory on a D-brane has no gravity, similar to
theories of entangled electrons of interest to us.
• In d = 2, we obtain strongly-interacting CFT3s. These are
“dual” to string theory on anti-de Sitter space: AdS4.
Tuesday, January 21, 14
![Page 59: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/59.jpg)
1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
![Page 60: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/60.jpg)
1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
![Page 61: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/61.jpg)
��c
Quantum critical point with non-local entanglement in spin wavefunction
=1⌅2
⇥���⇥⇤⌅�
��� ⇤⇥⌅⇤
Tuesday, January 21, 14
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Classicalspin
waves
Dilutetriplon
gas
Quantumcritical
Neel order
Tuesday, January 21, 14
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Classicalspin
waves
Dilutetriplon
gas
Quantumcritical
Neel order
S. Sachdev and J. Ye, Phys. Rev. Lett. 69, 2411 (1992).
A. V. Chubukov, S. Sachdev, and J. Ye, Phys. Rev. B 49, 11919 (1994).
Thermally excited spin waves
Thermally excited triplon particles
Tuesday, January 21, 14
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Classicalspin
waves
Dilutetriplon
gas
Quantumcritical
Neel order
S. Sachdev and J. Ye, Phys. Rev. Lett. 69, 2411 (1992).
A. V. Chubukov, S. Sachdev, and J. Ye, Phys. Rev. B 49, 11919 (1994).
Thermally excited spin waves
Thermally excited triplon particles
Needed: Accurate theory of quantum critical dynamics
without quasiparticles
Tuesday, January 21, 14
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A 2+1 dimensional system at its
quantum critical point
String theory at non-zero temperatures
Tuesday, January 21, 14
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A 2+1 dimensional system at its
quantum critical point
A “horizon”, similar to the surface of a black hole !
String theory at non-zero temperatures
Tuesday, January 21, 14
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Objects so massive that light is gravitationally bound to them.
Black Holes
Tuesday, January 21, 14
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Horizon radius R =2GM
c2
Objects so massive that light is gravitationally bound to them.
Black Holes
In Einstein’s theory, the region inside the black hole horizon is disconnected from
the rest of the universe.
Tuesday, January 21, 14
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Around 1974, Bekenstein and Hawking showed that the application of the
quantum theory across a black hole horizon led to many astonishing
conclusions
Black Holes + Quantum theory
Tuesday, January 21, 14
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_
Quantum Entanglement across a black hole horizon
Tuesday, January 21, 14
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_
Quantum Entanglement across a black hole horizon
Tuesday, January 21, 14
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_
Quantum Entanglement across a black hole horizon
Black hole horizon
Tuesday, January 21, 14
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_
Black hole horizon
Quantum Entanglement across a black hole horizon
Tuesday, January 21, 14
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Black hole horizon
Quantum Entanglement across a black hole horizon
There is a non-local quantum entanglement between the inside
and outside of a black hole
Tuesday, January 21, 14
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Black hole horizon
Quantum Entanglement across a black hole horizon
There is a non-local quantum entanglement between the inside
and outside of a black hole
Tuesday, January 21, 14
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Quantum Entanglement across a black hole horizon
There is a non-local quantum entanglement between the inside
and outside of a black hole
This entanglement leads to ablack hole temperature
(the Hawking temperature)and a black hole entropy (the Bekenstein entropy)
Tuesday, January 21, 14
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A “horizon”,whose temperature and entropy equal
those of the quantum critical point
String theory at non-zero temperatures
A 2+1 dimensional system at its
quantum critical point
Tuesday, January 21, 14
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Friction of quantum criticality = waves
falling into black brane
A “horizon”,whose temperature and entropy equal
those of the quantum critical point
String theory at non-zero temperatures
A 2+1 dimensional system at its
quantum critical point
Tuesday, January 21, 14
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A 2+1 dimensional system at its
quantum critical point
An (extended) Einstein-Maxwell provides successful description of
dynamics of quantum critical points at non-zero temperatures (where no other methods apply)
A “horizon”,whose temperature and entropy equal
those of the quantum critical point
String theory at non-zero temperatures
Tuesday, January 21, 14
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0 2 4 6 8 10 12 14
0.25
0.30
0.35
0.40
0.45
0.50
wê2pT
sHwLêsQ
Predictions of holographic theory,
after analytic continuation to real frequencies
W. Witczak-Krempa, E. Sorensen, and S. Sachdev, arXiv:1309.2941
See also K. Chen, L. Liu, Y. Deng, L. Pollet, and N. Prokof’ev, arXiv:1309.5635
Black hole predictions for quantum critical dynamics�(!
)/(e
2/h
)
Tuesday, January 21, 14
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1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
![Page 82: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/82.jpg)
1. Key ideas from quantum mechanics
2. Many-particle systems: the concept
of a quasiparticle
3. Quantum phases of a magnetic insulator Quantum critical point without quasiparticles
4. Connections to string theory
5. Non-zero temperatures and black holes
6. The high temperature superconductors
Outline
Tuesday, January 21, 14
![Page 83: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/83.jpg)
YBa2Cu3O6+xTuesday, January 21, 14
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Julian Hetel and Nandini Trivedi, Ohio State University
Nd-Fe-B magnets, YBaCuO superconductor
Tuesday, January 21, 14
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Julian Hetel and Nandini Trivedi, Ohio State University
Nd-Fe-B magnets, YBaCuO superconductor
Tuesday, January 21, 14
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Julian Hetel and Nandini Trivedi, Ohio State University
Nd-Fe-B magnets, YBaCuO superconductor
Tuesday, January 21, 14
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Julian Hetel and Nandini Trivedi, Ohio State University
Nd-Fe-B magnets, YBaCuO superconductor
Tuesday, January 21, 14
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Ishida, Nakai, and HosonoarXiv:0906.2045v1
Iron pnictides: a new class of high temperature superconductors
Tuesday, January 21, 14
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TSDW Tc
T0
2.0
0
α"
1.0 SDW
Superconductivity
BaFe2(As1-xPx)2
AF
Resistivity⇠ ⇢0 +AT↵
S. Kasahara, T. Shibauchi, K. Hashimoto, K. Ikada, S. Tonegawa, R. Okazaki, H. Shishido, H. Ikeda, H. Takeya, K. Hirata, T. Terashima, and Y. Matsuda,
Physical Review B 81, 184519 (2010)Tuesday, January 21, 14
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TSDW Tc
T0
2.0
0
α"
1.0 SDW
Superconductivity
BaFe2(As1-xPx)2
AF
Resistivity⇠ ⇢0 +AT↵
S. Kasahara, T. Shibauchi, K. Hashimoto, K. Ikada, S. Tonegawa, R. Okazaki, H. Shishido, H. Ikeda, H. Takeya, K. Hirata, T. Terashima, and Y. Matsuda,
Physical Review B 81, 184519 (2010)
Neel (AF) and “nematic” order
Tuesday, January 21, 14
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TSDW Tc
T0
2.0
0
α"
1.0 SDW
Superconductivity
BaFe2(As1-xPx)2
AF
Resistivity⇠ ⇢0 +AT↵
S. Kasahara, T. Shibauchi, K. Hashimoto, K. Ikada, S. Tonegawa, R. Okazaki, H. Shishido, H. Ikeda, H. Takeya, K. Hirata, T. Terashima, and Y. Matsuda,
Physical Review B 81, 184519 (2010)
Neel (AF) and “nematic” order
Tuesday, January 21, 14
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TSDW Tc
T0
2.0
0
α"
1.0 SDW
Superconductivity
BaFe2(As1-xPx)2
AF
Resistivity⇠ ⇢0 +AT↵
S. Kasahara, T. Shibauchi, K. Hashimoto, K. Ikada, S. Tonegawa, R. Okazaki, H. Shishido, H. Ikeda, H. Takeya, K. Hirata, T. Terashima, and Y. Matsuda,
Physical Review B 81, 184519 (2010)
SuperconductorBose condensate of pairs of electrons
Tuesday, January 21, 14
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TSDW Tc
T0
2.0
0
α"
1.0 SDW
Superconductivity
BaFe2(As1-xPx)2
AF
Resistivity⇠ ⇢0 +AT↵
S. Kasahara, T. Shibauchi, K. Hashimoto, K. Ikada, S. Tonegawa, R. Okazaki, H. Shishido, H. Ikeda, H. Takeya, K. Hirata, T. Terashima, and Y. Matsuda,
Physical Review B 81, 184519 (2010)
Ordinary metal(Fermi liquid)
Tuesday, January 21, 14
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TSDW Tc
T0
2.0
0
α"
1.0 SDW
Superconductivity
BaFe2(As1-xPx)2
AF
Resistivity⇠ ⇢0 +AT↵
S. Kasahara, T. Shibauchi, K. Hashimoto, K. Ikada, S. Tonegawa, R. Okazaki, H. Shishido, H. Ikeda, H. Takeya, K. Hirata, T. Terashima, and Y. Matsuda,
Physical Review B 81, 184519 (2010)
StrangeMetal
no quasiparticles,Landau-Boltzmann theory
does not apply
Tuesday, January 21, 14
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Quantum criticality of Ising-nematic ordering in a metal
x
yOccupied states
Empty states
A metal with a Fermi surfacewith full square lattice symmetry
Tuesday, January 21, 14
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Quantum criticality of Ising-nematic ordering in a metal
Neel (AF) and “nematic” order
x
y
Spontaneous elongation along x direction
Tuesday, January 21, 14
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Spontaneous elongation along y direction
Quantum criticality of Ising-nematic ordering in a metal
Neel (AF) and “nematic” order
x
y
Tuesday, January 21, 14
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rrc
Zero temperature phase diagram as a
function of some parameter r
��⇥ = 0⇥�⇤ �= 0
or
Quantum criticality of Ising-nematic ordering in a metal
Tuesday, January 21, 14
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T
Phase diagram as a function of T and r
rrc
TI-nStrangeMetal
Quantum criticality of Ising-nematic ordering in a metal
Fermi liquid
or
Fermi liquid
Tuesday, January 21, 14
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T
Phase diagram as a function of T and r
rrc
TI-nStrangeMetal
Quantum criticality of Ising-nematic ordering in a metal
Fermi liquid
or
Fermi liquid
Strongly-coupled“non-Fermi liquid”
metal with no quasiparticles
Tuesday, January 21, 14
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Strongly-coupled quantum critical points lead to a novel regime of quantum dynamics without quasiparticles.
The simplest examples are CFT3s realized in experiments on ultracold bosons and in model antiferromagnets.
Methods of string theory, and black hole dynamics, provide a quantitative understanding of quantum Monte studies of quantum critical points in condensed matter.
Exciting recent progress on the description of metallic states without quasiparticles, via quantum field theory and holography
Tuesday, January 21, 14
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Strongly-coupled quantum critical points lead to a novel regime of quantum dynamics without quasiparticles.
The simplest examples are CFT3s realized in experiments on ultracold bosons and in model antiferromagnets.
Methods of string theory, and black hole dynamics, provide a quantitative understanding of quantum Monte studies of quantum critical points in condensed matter.
Exciting recent progress on the description of metallic states without quasiparticles, via quantum field theory and holography
Tuesday, January 21, 14
![Page 103: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/103.jpg)
Strongly-coupled quantum critical points lead to a novel regime of quantum dynamics without quasiparticles.
The simplest examples are CFT3s realized in experiments on ultracold bosons and in model antiferromagnets.
Methods of string theory, and black hole dynamics, provide a quantitative understanding of quantum Monte studies of quantum critical points in condensed matter.
Exciting recent progress on the description of metallic states without quasiparticles, via quantum field theory and holography
Tuesday, January 21, 14
![Page 104: Quantum mechanics without particlesqpt.physics.harvard.edu/talks/niser14.pdf · 2014-01-21 · Principles of Quantum Mechanics: 1I. Quantum Entanglement _ Einstein-Podolsky-Rosen](https://reader034.vdocuments.site/reader034/viewer/2022043019/5f3b14897febed590f75d4f4/html5/thumbnails/104.jpg)
Strongly-coupled quantum critical points lead to a novel regime of quantum dynamics without quasiparticles.
The simplest examples are CFT3s realized in experiments on ultracold bosons and in model antiferromagnets.
Methods of string theory, and black hole dynamics, provide a quantitative understanding of quantum Monte studies of quantum critical points in condensed matter.
Exciting recent progress on the description of metallic states without quasiparticles, via quantum field theory and holography
Tuesday, January 21, 14