1. 18 56 Quantum Information Science: A Second Quantum Revolution Christopher Monroe www.iontrap.umd.edu Joint Quantum Institute University of Maryland Department of Physics

2. Joint Quantum Institute Quantum science for tomorrow’s technology

3. Computer Science and Information Theory Alan Turing (1912-1954) universal computing machines Claude Shannon (1916-2001) quantify information: the bit Charles Babbage (1791-1871) mechanical difference engine

4. ENIAC (1946)

5. The first solid-state transistor (Bardeen, Brattain & Shockley, 1947)

6. Source: Intel

7. “When we get to the very, very small world – say circuits of seven atoms - we have a lot of new things that would happen that represent completely new opportunities for design. Atoms on a small scale behave like nothing on a large scale, for they satisfy the laws of quantum mechanics…” “There's Plenty of Room at the Bottom” (1959) Richard Feynman

8. Albert Einstein (1879-1955) Erwin Schrödinger (1887-1961) Werner Heisenberg (1901-1976) Quantum Mechanics: A 20 th century revolution in physics Why doesn’t the electron collapse onto the nucleus of an atom? Why are there thermodynamic anomalies in materials at low temperature? Why is light emitted at discrete colors?..

9. The Golden Rules of Quantum Mechanics of Quantum Mechanics 2. Rule #1 holds as long as you don’t look! [1] [0] [0] & [1] or 1.Quantum objects are waves and can be in states of superposition. “qubit”: [0] & [1]

10. Wave mechanics Quantized energy Low temperature phenomena e.g., superfluidity, BEC Quantum Electrodynamics (QED) Nuclear physics Particle physics Most of 20 th century quantum physics concerned with rule #1: e.g., magnetism of the electron: g e = 2.00231930439 (agrees w/ theory to 12 digits)

11. Quantum Mechanics Information Theory Quantum Information Science A new science for the 21 st Century? 20 th Century 21 st Century

12. What if we store information in quantum systems? classical bit: 0 or 1 quantum bit: a [0] + b [1]

13. GOOD NEWS… quantum parallel processing on 2 N inputs Example: N=3 qubits  =a 0 [000] + a 1 [001] + a 2 [010] + a 3 [011] a 4 [100] + a 5 [101] + a 6 [110] + a 7 [111] f(x) …BAD NEWS… Measurement gives random result e.g.,   [101] f(x)

14. depends on all inputs quantum logic gates …GOOD NEWS! quantum interference Deutsch (1985) Shor (1994) Grover (1996) fast number factoring N = p  q fast database search

15. Quantum Computers and Computing Institute of Computer Science Russian Academy of Science ISSN 1607-9817 Quantum Computers and Computing Institute of Computer Science Russian Academy of Science ISSN 1607-9817

16. depends on all inputs quantum logic gates [0] [0]  [0] [0] [0] [1]  [0] [1] [1] [0]  [1] [1] [1] [1]  [1] [0] e.g., [0] + [1] [0]  [0][0] + [1][1] quantum XOR gate: superposition  entanglement [0]  [0] + [1] [1]  [1]  [0] quantum NOT gate: ( ) …GOOD NEWS! quantum interference

17. John Bell (1964) Any possible “completion” to quantum mechanics will violate local realism just the same Ψ = [↑][↓]  [ ↓ ][ ↑ ]

18. [did decay][Alive] + [didn’t decay][Dead] Schrödinger’s Cat (1935)

19. Entanglement: Quantum Coins Two coins in a quantum superposition [H][H] & [T][T] 1

20. Entanglement: Quantum Coins Two coins in a quantum superposition [H][H] & [T][T] 0 1

21. Entanglement: Quantum Coins Two coins in a quantum superposition [H][H] & [T][T] 0 1 0

22. Entanglement: Quantum Coins Two coins in a quantum superposition [H][H] & [T][T] 0 1 0 1

23. Entanglement: Quantum Coins Two coins in a quantum superposition [H][H] & [T][T] 0 1 0 1 1

24. Entanglement: Quantum Coins Two coins in a quantum superposition [H][H] & [T][T] 0 1 0 1 1 1

25. Entanglement: Quantum Coins Two coins in a quantum superposition [H][H] & [T][T] 0 1 0 1 1 1 0...

26. Comments on quantum coins: 1.Doesn’t violate relativity (superluminal communication): no information transmitted in a random bit stream! 2. Application: Quantum Cryptography (a secure “one-time pad”) + plaintext KEY ciphertext KEY plaintext +

27. Quantum Superposition From Taking the Quantum Leap, by Fred Alan Wolf

28. Quantum Superposition From Taking the Quantum Leap, by Fred Alan Wolf

29. Quantum Superposition From Taking the Quantum Leap, by Fred Alan Wolf

30. Quantum Entanglement “Spooky action-at-a-distance” (A. Einstein) From Taking the Quantum Leap, by Fred Alan Wolf

31. Quantum Entanglement “Spooky action-at-a-distance” (A. Einstein) From Taking the Quantum Leap, by Fred Alan Wolf

32. Quantum Entanglement “Spooky action-at-a-distance” (A. Einstein) From Taking the Quantum Leap, by Fred Alan Wolf

33. Quantum Entanglement “Spooky action-at-a-distance” (A. Einstein) From Taking the Quantum Leap, by Fred Alan Wolf

35. NIST-Boulder (D. Wineland) U. Innsbruck (R. Blatt) U. Maryland & JQI (C.M.) Trapped Atomic Ions ~2  m seven Yb + ions

36. 171 Yb + qubit [][] [][] ~GHz Hyperfine Ground States Electronic Excited State (  ~ 8 nsec) “bright” # photons collected in 100 s 0510152025 0 1 Probability [][]

37. 99.7% detection efficiency 0510152025 Probability # photons collected in 100 s 0 1 | | “dark” [][] [][] ~GHz Hyperfine Ground States 171 Yb + qubit Electronic Excited State (  ~ 8 nsec)

38. 0 1 2 [][] 0 1 2 [][] ~MHz Mapping: ( a [  ]  + b [  ]) [0] m  [  ] ( a [0] m + b [1] m ) Cirac and Zoller, Phys. Rev. Lett. 74, 4091 (1995) ~GHz Hyperfine Ground States Electronic Excited State

39. Cirac and Zoller, Phys. Rev. Lett. 74, 4091 (1995) Trapped Ion Quantum Computer Internal states of these ions entangled

42. 1 mm

45. Ion Trap Chips Lucent/MIT Al/Si/SiO 2 Maryland/LPS GaAs/AlGaAs Sandia W/Si NIST-Boulder Au/Quartz

46. Teleportation of a single atom from here… to here…

47. we need more qubits..

49. Albert Chang (Duke Univ.) Single electron quantum dots

50. Phosphorus atoms in Silicon B. Kane, Nature 393, 133 (1998) LPS/U. Maryland Los Alamos entire country of Australia qubit stored in 31 P nuclear spin ( 31 P: spin) ( 28 Si: no spin) Si lattice

51. Superconducting currents H. Mooij (Delft, Netherlands) quantized flux qubit states

52. Superconducting currents R. Schoelkopf, Michel Devoret Steve Girvin (Yale Univ.) quantized charge qubit states

53. Doped impurities in glass Nitrogen + Vacancy impurity in diamond Fluorescence of an array of single impurities in diamond J. Wrachtrup (Stuttgart)

54. 1. Individual atoms and photons ion traps atoms in optical lattices cavity-QED 2. Superconductors Cooper-pair boxes (charge qubits) rf-SQUIDS (flux qubits) 3. Semiconductors quantum dots 4. Other condensed-matter electrons floating on liquid helium single phosphorus atoms in silicon scales works Quantum Computer Physical Implementations

55. N=10 28 N=1

57. Quantum Mechanics Information Theory Quantum Information Science A new science for the 21 st Century? 20 th Century 21 st Century Physics Chemistry Computer Science Electrical Engineering Mathematics Information Theory

59. Postdocs Ming-Shien Chang Peter Maunz Dmitry Matsukevich Kihwan Kim Wes Campbell Le Luo Qudsia Quraishi Undergrads Guillermo Silva Andrew Chew Collaborators Luming Duan (Michigan) Jim Rabchuk (W. Illinois) Keith Schwab (Cornell) Vanderlei Bagnato (U. Sao Paulo) Grad Students Dave Hayes Rajibul Islam Simcha Korenblit Andrew Manning Jonathan Mizrahi Steven Olmschenk Jon Sterk http://iontrap.umd.edu