Build Your Own Quantum Computer for Fun and Profit!

Stephen Granade

Bits are 1s and 0s (i.e. base 2)

16 8 4 2 1

16 2 1 + + = 191 00 11

Save Us, Gordon Moore!

Parallel ComputationTakes More Space

Photo credit: pure_martin

Light Polarization States

Vertical light:

Horizontal light:

A mix:

2

1

2

1

Amplitudes

Square for probabilities: 2

1,

2

1

What’s Going On With The 3 Polarizers

Vertical polarizer:

Horizontal polarizer: nada

What’s Going On With The 3 Polarizers

Vertical polarizer:

45 degree polarizer:

Horizontal polarizer:

2

1

2

1

Bits Hold 1 NumberQubits Can Hold All Numbers!

111110

101100

011010

001000

81

101

3-Bit Number 3-Qubit Number

Superposition makesthis possible

Tangent: Entanglement Happens When One Qubit’s State Depends on

Another’s

11002

1 01002

1

Entangled Not Entangled

If you measure the firstqubit and it’s 0, you knowthe second qubit is 0 too.

They’re entangled!

If you measure the firstqubit and it’s 0, you don’tknow the second qubit.They’re independent!

You Can Add All Numbers At Once!

1001101

11010121003

11410301200

441

111001004

1

111001004

1

Classical Computer Quantum Computer

Public

It’s Just an Algorithm

Private

n

n

qped

qpn

qp

d

e

modencryptmsg

modmsgencrypt

11mod1

prime) largevery (,Choose

Turning Factoring into Period Finding

,mod,mod

,mod,mod43

2

nxnx

nxnx

If n has the factors p and q,then, if you pick a random x,the above sequence has aperiod that evenly dividesinto (p-1)(q-1)

Leonhard Euler

Shor’s Algorithm is Fast

3/1log2O n

3logO n

Classical factoring

Shor’s Algorithm

Grover’s Algorithm Finds Stuff QuicklySearches unsorted data

Photo credit: seanabrady

Number of items Approx. Speedup

100 10

1,000 32

10,000 100

100,000 316

1,000,000 1000

10,000,000 3162

100,000,000 10000

1,000,000,000 31623

Decoherence Smears Out States

dead2

1alive

2

1

dead

There are Lots of Ways to Make a Quantum Computer

PhotonsTrapped Ions

Optical Lattice

Liquid NMRSpintronics

7-Qubit Computer from IBM

15

3 5

Factored

2001. Chuang et. al.

First Qubyte from Innsbruck

Quantum Computer Onna Chip

Sadly I have no good pictures of the group or its research besides this graphic from the cover of Science

D-Wave…maybe