Power and strangeness of the quantum

Quantum theory has opened to us the microscopic world of particles, atoms and photons…

….and has given us the keys of modern technologies

This is a theory whose logics challenges our classical intuition, even if its strangeness remains generally veiled at the

macroscopic level

Recent experiments lead us to believe that the microscopic strangeness of quantum physics could be harnessed to realize new tools for communicating, computing or measuring things

better…

atoms

Molecules and chemistry

solids

cosmology

Quantum physics: a theory of everything

Computers

Lasers

Moore’s law: every 18 months computer power doubles

faster = smaller

Pentium 4 (2002)

1 atom

ENIAC (1947)

from: Gordon E. Moore “No exponential is forever…“

Progress in technology …

Atomic clocks and GPS

Geo-localization within 1 meter on surface of earth!

Light is a wave and an ensemble of photons (Einstein 1905)

Atoms are particles and matter waves (de Broglie, 1923)

Quantum physics is based on the wave-particle duality and the superposition

principle

Quantum physics and the superposition principle…

x y

|>=|X> + |Y>

Superposition of positions…

+

…or superposition of atomic states of

different energies …

Here or there?

The measurement: a random result

God is playing dice

Environment

or

Decoherence

The environment «spies » on quantum systems and destroys their quantum coherence very efficiently

‘

Thought experiments

Einstein, Bohr and their Photon Box…

How thoughts experiments controlling a « zoo of particles » have become real

New quantum technologies:

Tuneable Lasers

Fast computers

Supraconducting materials

«Particle control in a quantum world»

The Boulder experiments (David Wineland)

The Paris experiments (SH)

«Particle control in a quantum world»

Why is it important to be able to manipulate single quantum particles?

Curiosity: is it possible? How does Nature behaves at this level?

Small systems reacts faster and pack more information per unit volume, leading to more powerful devices (Moore’s law)

We never experiments with single electrons, atoms or small molecules…In thought experiments we assume that we do. It always results in ridiculous consequences… » (Schrödinger 1952)

Quantum physics makes a wide range of new states accessible for possible applications

More powerful computers and/or simulators

(quantum logic)

More secrete communications

(quantum cryptography)

More precise measurements

(quantum metrology)

1960 1970 1980 1990 2000 2010 2020 year

1 atom per bit num

ber

of ato

ms p

er

bit

~ 2017

faster = smaller

How many atoms per bit?

Pentium 4 (2002)

1 atom

ENIAC (1947)

1019

1015

1011

107

103

100

Pentium 4

R. W. Keyes, IBM J. R&D 32, 26 (1988)

Progress in technology …

22 nm transistor

A computer in a Schrödinger cat state to break the RSA code?

Quantum computers would exploit state superpositions and entanglement in ensemble of real or artificial atoms to compute more efficiently

Decoherence is the big challenge.

Ways to correct for it

are investigated.

Proof of principle

experiments under way with small

ensembles of atoms

Quantum simulators

Atoms in optical lattices to simulate solid state structures

1,E-18

1,E-17

1,E-16

1,E-15

1,E-14

1,E-13

1,E-12

1,E-11

1,E-10

1,E-09

1,E-08

1,E-07

1,E-06

1,E-05

1,E-04

1,E-03

1,E-02

1,E-01

1,E+00

1,E-06 1,E-03 1,E+00 1,E+03 1,E+06 1,E+09 1,E+12 1,E+15

Frequency [Hz]

Another illustration of the law “smaller is faster and better”: Clock speed and accuracy vs time

Fractional accuracy at one day

Sundial Period = 1 day

Accuracy ≈ 1-10 minutes

Pendulum Period ≈ 1 s

Accuracy ≈ 10 ms

Quartz Period ≈ 100 ns Accuracy ≈ 10-10

Cesium fountain Period ≈ 108 ps

Accuracy ≈ 3x10-16 Al+ optical Period ≈ 1 fs

Accuracy ≈ 8.6x10-18

10-6 10-3 100 103 106 109 1012 1015

10-3

10-6

10-9

10-12

10-15

10-18

1

Towards 10-18

accuracy?

27Al+ vs. 27Al+

C.-W. Chou, et al.

PRL 104, 070802 (2010)

Comparing two single ion clocks (David Wineland group at NIST)

0 10-18

0 10-18

3 10-18

7 10-18

10 10-18

16 10-18

20 10-18

27 10-18

33 10-18

38 10-18

38 10-18

36 10-18

General relativity test: clocks 33 cm apart in gravitational fields tick at different rates!

Measured:

Expected: (33 cm)

(37 +/- 15 cm)

33

cm

C. W. Chou, et al.

Science 329, 1630 (2010)

Practical applications for clocks keeping time within a handful of seconds in the age of

the Universe?

Better GPS able to track very small motions (at millimeter scale?)

Geodesic surveys (oil prospection?)

Earthquakes warnings?

Unpredictability of blue sky research

Laser (1960)

Highly transparent

optical fibers

(1970’s)

Transistors and Integrated circuits (1949 - 1990’s)

Global communication

network

Towards a quantum internet?

Magnetic resonance imaging (MRI)

Magnetic resonance

(1946)

+

Superconducting magnets (1970’s)

+

Fast small Computers (1970’s)

It is hard to make predictions, especially about the future…

(Attributed to Niels Bohr)

…and the past teaches us that wonderful applications always emerge serendipitously from blue sky research…

… but one thing is sure: without basic research, novel technologies cannot be

invented…