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Evaporating Black Holes Coupled to a Thermal Bath Shan-Ming Ruan - - PowerPoint PPT Presentation

Evaporating Black Holes Coupled to a Thermal Bath Shan-Ming Ruan Perimeter Institute & University of Waterloo Nov 2020 Strings and Fields 2020 arXiv:1911.03402,2007.11658 with Vincent Chen, Zachary Fisher, Juan Hernandez, and Robert C.


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Evaporating Black Holes Coupled to a Thermal Bath

Shan-Ming Ruan Perimeter Institute & University of Waterloo

Nov 2020 Strings and Fields 2020

arXiv:1911.03402,2007.11658 with Vincent Chen, Zachary Fisher, Juan Hernandez, and Robert C. Myers

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BH coupled to a Thermal Bath Shan-Ming Ruan (PI)

❖ Motivations & Background ❖ Doubly Holographic Models ❖ Quantum Extremal Surfaces and Islands ❖ Entanglement Wedge Reconstruction

Outline

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BH coupled to a Thermal Bath Shan-Ming Ruan (PI)

01.Background- Page Curve

S

t

tPage

Page Curve (unitarity)

Fine Grained entropy Coarse Grained entropy

Sradiation = − tr( ̂ ρ ln ̂ ρ)

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SBH = A(t) 4GN

Evaporating Black Hole

Hawking’s Result

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  • 01. Generalized Entropy and QES

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Need a correct formula for entropy of BH/Radiations

See 1905.08762, Almheiri, Engelhardt, Marolf, Maxfield 1905.08255, Penington

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  • 01. Generalized Entropy and QES

Generalized entropy

Quantum extremal surfaces X Minimizing generalized entropy

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  • A

Ac

  • Minimal surface
  • Cauchy Slice

X Quantum Extremal Surface

ΣX Sgen[X] = A[X] 4GN + SvN(ΣX)

Sgen = MinX ExtX ( A[X] 4GN + SvN(ΣX))

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  • 01. Generalized Entropy and QES

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A correct formula for the fine grained entropy of Hawking radiation

Sradiation = MinX ExtX ( A[X] 4GN + SvN (Σradiation ∪ ΣIsland)) Island Formula:

see: 1908.10096 2006.06872

  • Radiations

t Island

Radiations

QES= Island

  • t < tPage

t ≥ tPage

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  • 02. Doubly Holographic Models

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How to calculate in the semi-classical limit?

Sgen

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  • 02. Doubly Holographic Models

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Two-dimensional CFT and JT gravity

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BH coupled to a Thermal Bath Shan-Ming Ruan (PI)

x− x+

± 1 πT0

t∞

AdS2

t u

u = 0

  • 02. AEMM Model

JT gravity + CFT Matter

f(u) = 1 πT0 tanh (πT0u) eternal black hole

ds2 = − 4f′ (y+)f′ (y−)dy+dy− (f(y+) − f(y−))

2

Vacuum solution: ϕ = 2 ¯ ϕr 1 − (πT0)

2 x+x−

x+ − x− < T++ > = 0 , < T−− > = 0 E0 ≡ ¯ ϕr 8πGN {f(u), u} = π ¯ ϕr 4GN T2

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AdS2

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  • 02. AEMM Model

ds2 = − 4f′ (y+)f′ (y−)dy+dy− (f(y+) − f(y−))

2

Put the black hole in a fridge!

x− x+

± 1 πT0

t∞

AdS2

t u

u = 0

eternal black hole Evaporating black hole

JT gravity + CFT Matter

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BH coupled to a Thermal Bath Shan-Ming Ruan (PI)

  • 02. AEMM Model

AEMM model (1905.08762, Almheiri, Engelhardt, Marolf, Maxfield)

Joint quench

Thermal Bath on half line JT gravity + CFT Matter It is a holographic model

2D Bath QMR QML

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1D dual system:

No gravity

Tb = 0

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Complexity on the brane Shan-Ming Ruan (PI)

  • 02. Doubly Holographic Model

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t∞

x± = ± 1 πT0

u = 0

x+ x−

QES New horizon

Shock wave QES

Gravitational Region Bath Region

QML QMR

Tb = 0

JT gravity + CFT Matter Thermal Bath

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  • 02. Doubly Holographic Model

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Page Curve

Unitary evolution of an evaporating black hole

uPage ≈ 2 3 T1 − T0 T1k + uHP 3 + k 6πT1 5 (T1 − T0)π + ⋯ uHP = 1 2πT1 log ( 8πT1 3k ) More details:1905.0876,1911.03402

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02. Model AEM4Z

model (1908.10996, Almheiri, Mahajan, Maldacena, Zhao)

AEM4Z

JT gravity + Holographic CFT It is a doubly holographic model! Holographic CFT on half line

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3D dual system: ( ) AdS3/BCFT2

See Dominik’s talk higher-dim construction

Takayanagi, 1105.5165

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  • 02. Doubly Holographic Models- Tb

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put a black hole in an oven Couple a black hole with a thermal bath

Tb ≠ 0

arXiv:2007.11658 with V.Chen, Z.Fisher, J.Hernandez, and R.Myers

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  • 02. Doubly Holographic Models- Tb

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Preheat the oven first! —Prepare a thermal state on cylinder Y = 1 πTb tanh(πTby)

Half cylinder Half line

˜ y± = ˜ u ± ˜ σ t∞

x± = ± 1 πT0

Ⅰ Ⅱ Ⅲ Ⅳ

y− = ∞

y+ − y− = 0

y

+

= ∞ u = 0

x+ x−

QES New horizon

Shock wave

QES

Gravitational Region Bath Region Purifying Region

Bifurcation surface

QML QMR

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  • 02. Doubly Holographic Models- Tb

Three equivalent descriptions

1D 2D 3D

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  • 03. QES and Islands

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A Solvable Model

Teff (u; Tb) = T2

b + (T2 1 − T2 b) e−ku

Thermalized Equilibrium Evaporating

Tb = T1 Tb < T1 Solutions

a = 2π k T 2

1 − T 2 b

ν = 2πTb k

E(u) = ¯ ϕrπ 4GN T2

eff(u)

Tb > T1

f (u, Tb) = 2 ka Iν(a)Kν (ae−ku/2) − Kν(a)Iν (ae−ku/2) I′

ν(a)Kν (ae−ku/2) − K′ ν(a)Iν (ae−ku/2)

k ≡ cGN 3 ¯ ϕr ≪ 1

: Temperature of BH after joint

T1

: Temperature of thermal bath

Tb

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Sgen(x+, x−) = ϕ 4GN + SvN , ∂x±Sgen = 0

Γeff (y−

QES) ≡

1 −

Tb Teff(y−

QES)

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QES with Islands

  • 03. QES and Islands

ϕ (x±) = ϕr (

2f′ (y−) x+ − x− + f′ ′ (y−) f′ (y−) )

SvN = SΩ−2g = SUHP − c

6 ∑

xi∈∂

log Ω(xi) Late time/Island Phase

;

x+

QES ≈ t∞ +

Γeff 4 − Γeff (t∞ − t) x−

QES ≈ t∞ −

8πTeff k (4 − Γeff) (t∞ − t)

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  • 02. Doubly Holographic Models- Tb

20 ˜ y± = ˜ u ± ˜ σ t∞

x± = ± 1 πT0

Ⅰ Ⅱ Ⅲ Ⅳ

y− = ∞

y+ − y− = 0

y+ = ∞ u = 0

x+ x−

QES New horizon

Shock wave

QES

Gravitational Region Bath Region Purifying Region

Bifurcation surface

QML QMR

Quantum Extremal Surface (QES)

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Thermalized Equilibrium Evaporating

Tb > T1 Tb = T1 Tb < T1 arXiv: 2007.11658

4GN ¯ ϕr Sgen

ku

uPage 2πTb 1 2 2πT1 3 2πTb Tb < T1 Tb = T1 Tb > T1 4πTbku 4 5 2π(Tb + T1)ku

  • 03. QES and Islands

Island Phase:

dSgen,late du ≈ − ¯ ϕr 4GN (1 − T2

b

T2

eff(u)) kπTeff(u)

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Equilibrium Status

T1 = Tb

x+

QES(t) =

k2 + π2T 2

1 ((πT1t) 2 − 1) + k ((πT1t) 2 + 1)

π2T 2

1 (π2T 2 1t2 + 2kt − 1)

x−

QES(t) =

k2 + π2T 2

1 ((πT1t) 2 − 1) + k ((πT1t) 2 + 1)

π2T 2

1 (−π2T 2 1t2 + 2kt + 1)

Sgen,late (T1) =

¯ ϕ 2GN (

k2 + π2T2

1 − k log [ϵ (k +

k2 + π2T2

1)])

Island outside horizon

;

x+

QES(t) < t∞ = x+ QES(t∞)

dx+

QES(t)

dt > 0

Constant

  • 03. QES and Islands
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Island outside horizon

Inside horizon

Tc1(u) < Tb < Tc2(u)

On the horizon

Tb = Tc1(u) or Tb = Tc2(u)

Outside horizon

Tb < Tc1(u) or Tb > Tc2(u)

Tc1(u) ≈ 1 − 2k πT1 Teff (y−

QES)

Tc2(u) ≈ 1 + 2k πT1 Teff (y−

QES)

ku ≳ log 1 − T2

1

T2

b

πT1 8k

At very late time, QES always moves outside horizon

  • 03. QES and Islands
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A correct formula for Radiation Island formula

  • 03. QES and Islands
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  • 03. Island Formula

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Island formula

Sgen[ρin] = Minχ Extχ ( A[χ] 4GN + SvN (Σin ∪ ΣIsland))

2D Bath (with radiation) QMR QML

ρout ρin

Sgen[ρout] = MinX ExtX ( A[X] 4GN + SvN(Σout))

Pure State: Equivalent

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  • 04. Entanglement Wedge Reconstruction

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Entanglement Wedge of + bath (Hawking radiation) +Purification QML Entropy of + bath (Hawking radiation) +Purification QML

Reconstruct the interior of BH after Page transition (Island Phase) 2D Bath (with radiation) QMR QML Purification

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  • 04. EWR- a finite bath interval

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Who knows information of the BH interior?

Only Hawking radiations is not enough How much Hawking radiation we need to reconstruct BH interior? Not all Hawking radiations are necessary What is the role of purification in EWR? Purification part may be also necessary

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  • 04. EWR- a finite bath interval

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SR = Sgen

QES−1 + S2−IR

SN = Sgen

QES′ ′ + S1−2 + S 1

2 −line

Reconstruct the interior of BH !

SR ≤ SN

subsystem: + part of the bath + Purification QML

[σ1, σ2]

Competing Channels

Island Phase

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  • 04. EWR- a finite bath interval

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subsystem: + part of the bath + Purification QML

[σ1, σ2]

The information encoded in Hawking radiation is redundant!

σ y+ u

uPage

y−

IR

s h

  • c

k

y2

˜ σ

Δσ(u)

˜ u

Purification

Tb > 0

Hawking radiation

Δσturn

σ y+ u

uPage

y−

IR

s h

  • c

k

y2

˜ σ

Δσ

˜ u

Purification

Tb = T1

Hawking radiation

σ2(u) ≳ T1 − T0 2k (T1 + Tb) + T1 4 (T1 + Tb) (u (1 − Tb T1 )

2

+ uHP (1 − T 2

b

T 2

1 )) +

log (

6Es cT1 )

2π (T1 + Tb) + ⋯

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  • 04. EWR- the role of purification

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SR = Sgen

QES−1 + S2

SN = Sgen

QES′ ′ + S1−2

Reconstruct the interior of BH !

SR ≤ SN

subsystem: + part of the bath QML

[σ1, σ2]

Only If :

Tb ≲ Tp ≈ T1 + T0 2 + k 2π log ( 6Es cT1 )

We also need the purification part when Tb ≥ Tp

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Remarks and Conclusions

  • The information of BH is not lost!
  • Surprising Result: Unitarity from semi-classical limit
  • Unitarity in the evolution of BH is universal !/?
  • Importance of Quantum Extremal Surface (QES)
  • Appearance of Island region at late time
  • Role of Purification in EWR
  • Redundancy of information in Hawking radiation
  • ………….

Lots to Explore!

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Thanks for your attention!

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