1. Quantum Criticality and Black Holes Talk online: sachdev.physics.harvard.edu Talk online: sachdev.physics.harvard.edu

2. Particle theorists Sean Hartnoll, KITP Christopher Herzog, Princeton Pavel Kovtun, Victoria Dam Son, Washington Sean Hartnoll, KITP Christopher Herzog, Princeton Pavel Kovtun, Victoria Dam Son, Washington

3. Markus Mueller Geneva Markus Mueller Geneva Condensed matter theorists Cenke Xu Harvard Cenke Xu Harvard Yang Qi Harvard Yang Qi Harvard

4. Three foci of modern physics Quantum phase transitions

5. Three foci of modern physics Quantum phase transitions Many QPTs of correlated electrons in 2+1 dimensions are described by conformal field theories (CFTs)

6. Three foci of modern physics Quantum phase transitions Black holes

7. Three foci of modern physics Quantum phase transitions Black holes Bekenstein and Hawking originated the quantum theory, which has found fruition in string theory

8. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics

9. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics Universal description of fluids based upon conservation laws and positivity of entropy production

10. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics

11. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics Canonical problem in condensed matter: transport properties of a correlated electron system

12. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics Canonical problem in condensed matter: transport properties of a correlated electron system New insights and results from detour unifies disparate fields of physics

13. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics

14. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics Many QPTs of correlated electrons in 2+1 dimensions are described by conformal field theories (CFTs)

15. Three foci of modern physics Black holes Hydrodynamics Quantum phase transitions Many QPTs of correlated electrons in 2+1 dimensions are described by conformal field theories (CFTs)

16. Ground state has long-range Néel order Square lattice antiferromagnet

17. J J/ Weaken some bonds to induce spin entanglement in a new quantum phase

18. M. Matsumoto, C. Yasuda, S. Todo, and H. Takayama, Phys. Rev.B 65, 014407 (2002). Quantum critical point with non-local entanglement in spin wavefunction

19. CFT3

20. TlCuCl 3

21. Pressure in TlCuCl 3

28. 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) TlCuCl 3 with varying pressure

29. Prediction of quantum field theory 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)

30. Half-filled band  Mott insulator with spin S = 1/2 Triangular lattice of [Pd(dmit) 2 ] 2  frustrated quantum spin system X[Pd(dmit) 2 ] 2 Pd SC X Pd(dmit) 2 t’ t t Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, J. Phys.: Condens. Matter 19, 145240 (2007)

32. Anisotropic triangular lattice antiferromagnet Neel ground state for small J’/J Broken spin rotation symmetry

33. Anisotropic triangular lattice antiferromagnet Possible ground state for intermediate J’/J N. Read and S. Sachdev, Phys. Rev. Lett. 62, 1694 (1989)

34. Anisotropic triangular lattice antiferromagnet Possible ground state for intermediate J’/J Valence bond solid (VBS) Broken lattice space group symmetry N. Read and S. Sachdev, Phys. Rev. Lett. 62, 1694 (1989)

35. Anisotropic triangular lattice antiferromagnet Broken lattice space group symmetry Possible ground state for intermediate J’/J Valence bond solid (VBS) N. Read and S. Sachdev, Phys. Rev. Lett. 62, 1694 (1989)

36. Anisotropic triangular lattice antiferromagnet Broken lattice space group symmetry Possible ground state for intermediate J’/J Valence bond solid (VBS) N. Read and S. Sachdev, Phys. Rev. Lett. 62, 1694 (1989)

37. Anisotropic triangular lattice antiferromagnet Broken lattice space group symmetry Possible ground state for intermediate J’/J Valence bond solid (VBS) N. Read and S. Sachdev, Phys. Rev. Lett. 62, 1694 (1989)

38. Magnetic Criticality T N (K) Neel order Me 4 P Me 4 As EtMe 3 As Et 2 Me 2 As Me 4 Sb Et 2 Me 2 P EtMe 3 Sb Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, J. Phys.: Condens. Matter 19, 145240 (2007) X[Pd(dmit) 2 ] 2 Et 2 Me 2 Sb (CO)

39. Magnetic Criticality T N (K) Neel order Me 4 P Me 4 As EtMe 3 As Et 2 Me 2 As Me 4 Sb Et 2 Me 2 P EtMe 3 Sb EtMe 3 P Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, J. Phys.: Condens. Matter 19, 145240 (2007) X[Pd(dmit) 2 ] 2 Et 2 Me 2 Sb (CO) Spin gap Spin gap

40. Magnetic Criticality T N (K) Neel order Me 4 P Me 4 As EtMe 3 As Et 2 Me 2 As Me 4 Sb Et 2 Me 2 P EtMe 3 Sb EtMe 3 P Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, J. Phys.: Condens. Matter 19, 145240 (2007) X[Pd(dmit) 2 ] 2 Et 2 Me 2 Sb (CO) VBS order Spin gap Spin gap

41. M. Tamura, A. Nakao and R. Kato, J. Phys. Soc. Japan 75, 093701 (2006) Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, Phys. Rev. Lett. 99, 256403 (2007) Observation of a valence bond solid (VBS) in ETMe 3 P[Pd(dmit) 2 ] 2 Spin gap ~ 40 K J ~ 250 K X-ray scattering

42. Magnetic Criticality T N (K) Neel order Me 4 P Me 4 As EtMe 3 As Et 2 Me 2 As Me 4 Sb Et 2 Me 2 P EtMe 3 Sb EtMe 3 P Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, J. Phys.: Condens. Matter 19, 145240 (2007) X[Pd(dmit) 2 ] 2 Et 2 Me 2 Sb (CO) VBS order Spin gap Spin gap

43. N. Read and S. Sachdev, Phys. Rev. Lett. 66, 1773 (1991) T. Senthil, A. Vishwanath, L. Balents, S. Sachdev and M.P.A. Fisher, Science 303, 1490 (2004). Cenke Xu and S. Sachdev, arXiv:0811.1220 Theoretical global phase diagram

44. N. Read and S. Sachdev, Phys. Rev. Lett. 66, 1773 (1991) T. Senthil, A. Vishwanath, L. Balents, S. Sachdev and M.P.A. Fisher, Science 303, 1490 (2004). Cenke Xu and S. Sachdev, arXiv:0811.1220 Theoretical global phase diagram CFTs

45. Theoretical global phase diagram CFTs N. Read and S. Sachdev, Phys. Rev. Lett. 66, 1773 (1991) T. Senthil, A. Vishwanath, L. Balents, S. Sachdev and M.P.A. Fisher, Science 303, 1490 (2004). Cenke Xu and S. Sachdev, arXiv:0811.1220

46. Magnetic Criticality T N (K) Neel order Me 4 P Me 4 As EtMe 3 As Et 2 Me 2 As Me 4 Sb Et 2 Me 2 P EtMe 3 Sb EtMe 3 P Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, J. Phys.: Condens. Matter 19, 145240 (2007) X[Pd(dmit) 2 ] 2 Et 2 Me 2 Sb (CO) Spin gap Spin gap VBS order

47. Magnetic Criticality T N (K) Neel order Me 4 P Me 4 As EtMe 3 As Et 2 Me 2 As Me 4 Sb Et 2 Me 2 P EtMe 3 Sb EtMe 3 P Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato, J. Phys.: Condens. Matter 19, 145240 (2007) X[Pd(dmit) 2 ] 2 Et 2 Me 2 Sb (CO) VBS order Spin gap Spin gap Quantum criticality described by CFT Quantum criticality described by CFT

48. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics

49. Black holes Three foci of modern physics Quantum phase transitions Hydrodynamics Canonical problem in condensed matter: transport properties of a correlated electron system

50. Black holes Three foci of modern physics Quantum phase transitions Hydrodynamics Canonical problem in condensed matter: transport properties of a correlated electron system

51. Indium Oxide films G. Sambandamurthy, A. Johansson, E. Peled, D. Shahar, P. G. Bjornsson, and K. A. Moler, Europhys. Lett. 75, 611 (2006). Superfluid-insulator transition

52. M. Greiner, O. Mandel, T. Esslinger, T. W. Hänsch, and I. Bloch, Nature 415, 39 (2002). Superfluid-insulator transition

55. Classical vortices and wave oscillations of the condensate Dilute Boltzmann/Landau gas of particle and holes

56. CFT at T>0

57. Quantum critical transport S. Sachdev, Quantum Phase Transitions, Cambridge (1999).

58. Quantum critical transport K. Damle and S. Sachdev, Phys. Rev. B 56, 8714 (1997).

59. Quantum critical transport P. Kovtun, D. T. Son, and A. Starinets, Phys. Rev. Lett. 94, 11601 (2005), 8714 (1997).

60. Indium Oxide films G. Sambandamurthy, A. Johansson, E. Peled, D. Shahar, P. G. Bjornsson, and K. A. Moler, Europhys. Lett. 75, 611 (2006). Superfluid-insulator transition

61. Three foci of modern physics Quantum phase transitions Black holes Hydrodynamics

62. Quantum phase transitions Three foci of modern physics Black holes New insights and results from detour unifies disparate fields of physics Canonical problem in condensed matter: transport properties of a correlated electron system

63. Hydrodynamics Quantum phase transitions Canonical problem in condensed matter: transport properties of a correlated electron system Three foci of modern physics Black holes New insights and results from detour unifies disparate fields of physics

64. Objects so massive that light is gravitationally bound to them. Black Holes

65. Objects so massive that light is gravitationally bound to them. Black Holes The region inside the black hole horizon is causally disconnected from the rest of the universe.

66. Black Hole Thermodynamics Bekenstein and Hawking discovered astonishing connections between the Einstein theory of black holes and the laws of thermodynamics

67. Black Hole Thermodynamics Bekenstein and Hawking discovered astonishing connections between the Einstein theory of black holes and the laws of thermodynamics

68. AdS/CFT correspondence The quantum theory of a black hole in a 3+1- dimensional negatively curved AdS universe is holographically represented by a CFT (the theory of a quantum critical point) in 2+1 dimensions Maldacena, Gubser, Klebanov, Polyakov, Witten 3+1 dimensional AdS space

69. AdS/CFT correspondence The quantum theory of a black hole in a 3+1- dimensional negatively curved AdS universe is holographically represented by a CFT (the theory of a quantum critical point) in 2+1 dimensions Maldacena, Gubser, Klebanov, Polyakov, Witten 3+1 dimensional AdS space A 2+1 dimensional system at its quantum critical point

70. AdS/CFT correspondence The quantum theory of a black hole in a 3+1- dimensional negatively curved AdS universe is holographically represented by a CFT (the theory of a quantum critical point) in 2+1 dimensions Maldacena, Gubser, Klebanov, Polyakov, Witten 3+1 dimensional AdS space Quantum criticality in 2+1 dimensions Black hole temperature = temperature of quantum criticality

71. AdS/CFT correspondence The quantum theory of a black hole in a 3+1- dimensional negatively curved AdS universe is holographically represented by a CFT (the theory of a quantum critical point) in 2+1 dimensions Strominger, Vafa 3+1 dimensional AdS space Quantum criticality in 2+1 dimensions Black hole entropy = entropy of quantum criticality

72. AdS/CFT correspondence The quantum theory of a black hole in a 3+1- dimensional negatively curved AdS universe is holographically represented by a CFT (the theory of a quantum critical point) in 2+1 dimensions 3+1 dimensional AdS space Quantum criticality in 2+1 dimensions Quantum critical dynamics = waves in curved space Maldacena, Gubser, Klebanov, Polyakov, Witten

73. AdS/CFT correspondence The quantum theory of a black hole in a 3+1- dimensional negatively curved AdS universe is holographically represented by a CFT (the theory of a quantum critical point) in 2+1 dimensions 3+1 dimensional AdS space Quantum criticality in 2+1 dimensions Friction of quantum criticality = waves falling into black hole Kovtun, Policastro, Son

74. Hydrodynamics Quantum phase transitions Three foci of modern physics Black holes New insights and results from detour unifies disparate fields of physics Canonical problem in condensed matter: transport properties of a correlated electron system

75. Hydrodynamics Quantum phase transitions Three foci of modern physics Black holes New insights and results from detour unifies disparate fields of physics Canonical problem in condensed matter: transport properties of a correlated electron system 1

76. Hydrodynamics of quantum critical systems 1. Use quantum field theory + quantum transport equations + classical hydrodynamics Uses physical model but strong-coupling makes explicit solution difficult

77. Hydrodynamics Quantum phase transitions Three foci of modern physics Black holes New insights and results from detour unifies disparate fields of physics Canonical problem in condensed matter: transport properties of a correlated electron system 1

78. Hydrodynamics Quantum phase transitions Three foci of modern physics Black holes New insights and results from detour unifies disparate fields of physics Canonical problem in condensed matter: transport properties of a correlated electron system 1 2

79. Hydrodynamics of quantum critical systems 1. Use quantum field theory + quantum transport equations + classical hydrodynamics Uses physical model but strong-coupling makes explicit solution difficult 2. Solve Einstein-Maxwell equations in the background of a black hole in AdS space Yields hydrodynamic relations which apply to general classes of quantum critical systems. First exact numerical results for transport co-efficients (for supersymmetric systems).

80. Hydrodynamics of quantum critical systems 1. Use quantum field theory + quantum transport equations + classical hydrodynamics Uses physical model but strong-coupling makes explicit solution difficult 2. Solve Einstein-Maxwell equations in the background of a black hole in AdS space Yields hydrodynamic relations which apply to general classes of quantum critical systems. First exact numerical results for transport co-efficients (for supersymmetric systems). Find perfect agreement between 1. and 2. In some cases, results were obtained by 2. earlier !!

81. Applications: 1. Magneto-thermo-electric transport near the superconductor-insulator transition and in graphene Hydrodynamic cyclotron resonance Nernst effect 2. Quark-gluon plasma Low viscosity fluid 3. Fermi gas at unitarity Non-relativistic AdS/CFT

82. 1. Magneto-thermo-electric transport near the superconductor-insulator transition and in graphene Hydrodynamic cyclotron resonance Nernst effect 2. Quark-gluon plasma Low viscosity fluid 3. Fermi gas at unitarity Non-relativistic AdS/CFT Applications:

83. The cuprate superconductors

84. Proximity to an insulator at 12.5% hole concentration

85. Cuprates

86. STM observations of VBS modulations by Y. Kohsaka et al., Nature 454, 1072 (2008)

87. CFT? Cuprates

88. Thermoelectric measurements CFT? Cuprates

89. Thermoelectric measurements CFT? Cuprates

90. S.A. Hartnoll, P.K. Kovtun, M. Müller, and S. Sachdev, Phys. Rev. B 76 144502 (2007)

92. Nernst experiment Vortices move in a temperature gradient Phase slip generates Josephson voltage 2eV J = 2  h n V E J = B x v H eyey HmHm Nernst signal e y = E y /| T |

93. S.A. Hartnoll, P.K. Kovtun, M. Müller, and S. Sachdev, Phys. Rev. B 76 144502 (2007)

94. Y. Wang, L. Li, and N. P. Ong, Phys. Rev. B 73, 024510 (2006). Theory for LSCO Experiments S.A. Hartnoll, P.K. Kovtun, M. Müller, and S. Sachdev, Phys. Rev. B 76 144502 (2007)

97. Applications: 1. Magneto-thermo-electric transport near the superconductor-insulator transition and in graphene Hydrodynamic cyclotron resonance Nernst effect 2. Quark-gluon plasma Low viscosity fluid 3. Fermi gas at unitarity Non-relativistic AdS/CFT

98. 1. Magneto-thermo-electric transport near the superconductor-insulator transition and in graphene Hydrodynamic cyclotron resonance Nernst effect 2. Quark-gluon plasma Low viscosity fluid 3. Fermi gas at unitarity Non-relativistic AdS/CFT Applications:

99. Au+Au collisions at RHIC Quark-gluon plasma can be described as “quantum critical QCD”

100. Phases of nuclear matter

101. S=1/2 Fermi gas at a Feshbach resonance

105. T. Schafer, Phys. Rev. A 76, 063618 (2007). A. TurlapovA. Turlapov, J. Kinast, B. Clancy, Le Luo, J. Joseph, J. E. Thomas, J. Low Temp. Physics 150, 567 (2008)B. Clancy. Joseph,as, J.p. Physic(2008)

106. T. Schafer, Phys. Rev. A 76, 063618 (2007). A. TurlapovA. Turlapov, J. Kinast, B. Clancy, Le Luo, J. Joseph, J. E. Thomas, J. Low Temp. Physics 150, 567 (2008)B. Clancy. Joseph,as, J.p. Physic(2008)

107. T. Schafer, Phys. Rev. A 76, 063618 (2007). A. TurlapovA. Turlapov, J. Kinast, B. Clancy, Le Luo, J. Joseph, J. E. Thomas, J. Low Temp. Physics 150, 567 (2008)B. Clancy. Joseph,as, J.p. Physic(2008)

108. T. Schafer, Phys. Rev. A 76, 063618 (2007). A. TurlapovA. Turlapov, J. Kinast, B. Clancy, Le Luo, J. Joseph, J. E. Thomas, J. Low Temp. Physics 150, 567 (2008)B. Clancy. Joseph,as, J.p. Physic(2008)

110. Theory for transport near quantum phase transitions in superfluids and antiferromagnets Exact solutions via black hole mapping have yielded first exact results for transport co- efficients in interacting many-body systems, and were valuable in determining general structure of hydrodynamics. Theory of Nernst effect near the superfluid- insulator transition, and connection to cuprates. Quantum-critical magnetotransport in graphene. Theory for transport near quantum phase transitions in superfluids and antiferromagnets Exact solutions via black hole mapping have yielded first exact results for transport co- efficients in interacting many-body systems, and were valuable in determining general structure of hydrodynamics. Theory of Nernst effect near the superfluid- insulator transition, and connection to cuprates. Quantum-critical magnetotransport in graphene. Conclusions