Exploring the Quantum World - Science in the Newssitn.hms.harvard.edu/wp-content/uploads/2014/09/quantumplantspulsars-1.pdfExploring the Quantum World: From Plants to Pulsars Michael

Exploring the Quantum World:

From Plants to Pulsars

Michael Goldman, Harvard University

Joey Goodknight, Harvard University

Tansu Daylan, Harvard University

Roadmap for the evening

1. Basics of quantum mechanics:

Superposition, uncertainty, and

other such weirdness

2. Quantum coherence in plants:

How quantum mechanics may give

photosynthesis a boost

3. Structure of supernovae:

Seeing quantum mechanics at

astrophysical scales

Michael

Goldman

Joey

Goodknight

Tansu Daylan

Classical vs. quantum

Unknown / CC BY-SA 3.0, Joseph Karl Stieler / Public domain, Steve Swayne / CC BY 2.0,

Derek Gleeson / CC BY-SA 3.0, 北京驱动文化传媒有限公司 / CC BY-SA 3.0, Skidmore College Orchestra / Public domain


Gullaume Paumler / CC BY-SA 2.0, Evan Amos / Public domain, Kristoferb / Public domain, Victorgrigas / CC BY-SA 3.0


Classical Quantum

Scale

Time

Math

Before ~1900 After ~1900*

Newton Schrödinger


There are certain phenomena that classical

physics cannot explain but quantum physics can.

The quantum explanation has unsettling

implications, like superposition and

wave-particle duality.

The classical view of particles

Particles have definite positions and obey deterministic laws.

Unknown / Public domain

The classical view of waves

Fjellanger Widerøe A.S, geralt / CC0 Public Domain

Diffraction Interference

The classical view of waves

Coherent Incoherent

Jordgette / CC BY-SA 3.0

Young’s double-slit experiment

Slits Screen

Constructive

interference

(maximum)

Destructive

interference

(minimum)

2 Slits 1 Slit

Intensity

What about matter?

? Baseball

Laser

# Balls

Questions?

What about (small) matter?

? e-

Electron gun

Laser

*simulate

Let’s do* the experiment!

e-

# Hits

Vertical

position

on screen

Observed time and again Light Electrons Neon Atoms Buckyballs (C60)

Netweb01 / CC BY-SA 3.0, Jordgette / CC BY-SA 3.0, R. Bach, et al., New J. Phys. 15, 033018 (2013),

F. Shimizu, et at., Phys. Rev. A 46, R17 (1992), M. Arndt, et al., Nature 401, 680 (1999), Mstroeck / CC BY-SA 3.0

Both a particle AND a wave

• Electron doesn’t exist only at one point, but has a chance of

being found over a extent of space

• Probability of the electron being found at a certain position

is determined probabilistically by its wavefunction

What’s going on?

3: Interference 4: Measurement at screen

1: Wavefunction/uncertainty

e-

2: Superposition

• Electron has probability of passing through either slit

• Wavefunction interferes with itself, just like water or light,

producing fringes at the screen

• Screen measures electron impact at one location, which is

determined probabilistically by wavefunction at screen

• Perform experiment many times to build up wavefunction

Probability

Questions?

Cover one slit

e-

As with light, one slit no interference

Introduce decoherence

e-

Waves from the two slits are not in phase

no interference

Detect electron going through slit

e-

One electron either goes through one slit

or the other, not both no interference

No detection

What about larger particles?

Very massive particles appear to behave

classically Quantum reduces to classical

{

λ ~ 1/mv

λ:

r:

Electron

1.2×10-11 m

2.8×10-15 m

O2 atom

5.5×10-10 m

2.8×10-10 m

Baseball

1.0×10-34 m

3.7×10-2 m

Takeaway message

Quantum mechanics has many unsettling implications:

• Superposition

• Probabilistic measurement

Nonetheless, there are many

parallels with our classical world.

How far can we push the boundary?











Michael

Goldman

Joey

Goodknight

Tansu Daylan

NASA public domain; Jhodlof Wikimedia Commons

? Photosynthesis

~1 gallon of gas per day

GREEN SULFUR BACTERIA

Chlorobaculum tepidum

gallon of gas per day

>100 meters down

kOchstudiO, Wikimedia Commons; Brocken Inaglory, Wikimedia Commons

José-manuel Benitos, Wikimedia Commons

1

FMO

CHEMISTRY

Antennae

Baseplate

Fenna Matthews Olson Complex:

Fenna-Mathews-Olsen (FMO)

Complex

A Protein

JulianAlexander, Wikimedia Commons

FMO

Chlorophyll

Protein Scaffolding

FMO

~C55 O5N4Mg

=Atom:

Wilfredo R. Rodriguez H., Wikimedia Commons; Benjah-bmm27 Wikimedia

Commons

Background: Chlorophyll

Background: Chlorophyll

Temporary Energy Storage

Questions?

CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMISTRY

Sugar:

Engel Group, University of Chicago

?

e-

?

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

CHEMIS

TRY CHEMISTRY

SO WHAT!?

Inside a Cell:

TimVickers, Wikimedia Commons

NATURE

The Air Force Research Laboratory’s Directed Energy Directorate, Wikimedia

Commons

Did Nature Evolve to be able

to Use

Quantum Mechanics

to Transfer Energy Better?

Did Nature Evolve to be able

to Use Quantum Mechanics to

Transfer Energy Better?











Michael

Goldman

Joey

Goodknight

Tansu Daylan

Image from http://chandra.harvard.edu

Outline

1. Pressure in a Classical Gas

2. Pressure in a Quantum Gas

3. Type IA Supernovae

Pressure in a Classical Gas

Let’s take a balloon filled with Hydrogen gas.


Heat

… and heat it.


Heat

The average kinetic energy of the molecules increases.


… and the balloon relaxes to a larger volume.


• Thermal Pressure

= Some Constant × Density × Temperature

Thermal Pressure

Temperature

QM101: Quantization

• Energy is quantized.

QM101: Quantization

Energy

Classical Quantum Mechanical

QM102: Pauli Exclusion

Principle

• No two fermions can occupy the same

state.


Principle

Energy


Principle

Energy


Principle

Energy


Principle

Energy


Principle

Energy

Pressure in a Quantum Gas

Now Let’s take another balloon filled with Hydrogen gas.


Distance

Now Let’s take another balloon filled with Hydrogen gas.


Distance

… and compress it!


Distance

… and compress it!


Energy

Distance

Let us replay the process in energy space.


Energy

Distance


Energy

Distance


Energy

Distance


Energy

Distance

.

.

.

Heat

Anyone feeling

pressured?

Nope,

just chilling!


• Degeneracy Pressure =

Some Constant × Some function of Density

Degeneracy Pressure

Temperature

Questions so far?

• Degeneracy Pressure =

Some Constant × Some Power of Density

Reminder:

• Thermal Pressure =

Some Constant × Density × Temperature

The Life Diary of a Star Conception

Birth

Babyhood Adolescence

Senility

Impotence

Puberty

Btw, we are here!

White Dwarf

Guys?

I am bored…

White Dwarf Gets a Big Buddy




White Dwarf’s Mass = 1.40 × Mass of our Sun









Oops…

The white dwarf explodes…


Conclusion

1. Pressure in a Classical Gas

2. Pressure in a Quantum Gas

3. Type IA Supernovae

Conclusion

• Quantum Mechanics is fundamental to the

formation of type IA supernovae!











Michael

Goldman

Joey

Goodknight

Tansu Daylan

Thank you! SITN would like to acknowledge the following

organizations for their generous support.

Harvard Medical School Office of Communications and External Relations

Division of Medical Sciences

The Harvard Graduate School of Arts and Sciences (GSAS)

The Harvard Graduate Student Council (GSC)

The Harvard Biomedical Graduate Students Organization (BGSO)

The Harvard/MIT COOP

Documents

Exploring the Quantum World - Science in the Newssitn.hms.harvard.edu/wp-content/uploads/2014/09/quantumplantspulsars-1.pdfExploring the Quantum World: From Plants to Pulsars Michael