IBM Q: building the first universal quantum computers for business and science. Federico Mattei Banking and Insurance Technical Leader, IBM Italy

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1 IBM Q: building the first universal quantum computers for business and science Federico Mattei Banking and Insurance Technical Leader, IBM Italy

2 Agenda Which problems can not be solved with classical computers? How do quantum computers work? Which problems can be solved with quantum computers? What can we do today with quantum computers?

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6 The Power of Exponential Scaling The inventor of chess showed it to the emperor of India, and the emperor was so impressed he said "Name your reward! The man responded. "Oh emperor, my wishes are simple. I only wish for this. For the next 64 days I will come back and for the first day please only give me one grain of rice for the first square of the chessboard, on the second day two grains for the next square, four for the next, eight for the next and so on for all 64 squares, with each square having double the number of grains as the square before." The emperor agreed, amazed that the man asked for such a small reward - or so he thought... 1 Day 1 Week 1 Month 64 Days ,435,455 18,446,744,073,709,551,615

7 The Traveling Salesman Problem Starting from city 1, the salesman must travel to all cities once before returning home The distance between each city is given, and is assumed to be the same in both directions Only the links shown are to be used Objective: minimize the total distance to be traveled Michael Held, Richard Shareshian, Richard Karp. IBM Archives.

8 Cryptography RSA Factoring Challenge RSA-100 has 100 decimal digits (330 bits). The number can be factorised in 72 minutes on overclocked to 3.5 GHz Intel Core2 Quad q9300 RSA-768 has 232 decimal digits (768 bits), and was factored on December 12, 2009 over the span of 2 years The CPU time spent on finding these factors by a collection of parallel computers amounted approximately to the equivalent of almost 2000 years of computing on a single-core 2.2 GHz AMD Opteron-based computer. RSA-1024 has 1,024 bits (309 decimal digits), and has not been factored so far. US$100,000 was previously offered for factorization. Source:

9 Molecular Dynamics, Drug Design & Materials This laptop could simulate a 25 electron system, Titan a 43 electron system but no classical computer ever built could simulate a 50 electron system exactly. Caffeine is a moderately sized molecule. It is more complex than water, but simpler than DNA or proteins. The complexity involved to simulate its energy, structure and interactions is beyond the capability of any computer with current technology.

10 NATURE ISN T CLASSICAL, DAMMIT, AND IF YOU WANT TO MAKE A SIMULATION OF NATURE, YOU D BETTER MAKE IT QUANTUM MECHANICAL, AND BY GOLLY, IT S A WONDERFUL PROBLEM, BECAUSE IT DOESN T LOOK SO EASY. RICHARD P. FEYNMAN Nature isn t classical, dammit, and if you want to make a simulation of nature, you d better make it quantum mechanical, and by golly, it s a wonderful problem, because it doesn t look so easy. -Richard P. Feynman

11 Agenda Which problems can not be solved with classical computers? How do quantum computers work? Which problems can be solved with quantum computers? What can we do today with quantum computers?

12 Superposition: each qubit in 2 states simultaneously BITS 1 QUBIT

13 Classical Information bit 1 bit 2 bit 3 bit Each bit is in a definite state, 0 or 1 Reading a bit does not change the state You can copy a bit All of the information of a bit is stored in that bit N bits in a classical machine represent ONLY 1 out of 2 N states

14 Quantum Information qubit 1 qubit 2 qubit 3 qubit 4 Entangled Quantum Information Each qubit is in a definite state: can be in superposition state 0> and 1> Reading a qubit can change the state You cannot copy a qubit state (no cloning) Information can be stored in correlations of qubits. Entanglement: non-classical correlation. N entangled qubits in superposition states span all 2 N states

15 Combination of Quantum and Classical Computing

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17 Agenda Which problems can not be solved with classical computers? How do quantum computers work? Which problems can be solved with quantum computers? What can we do today with quantum computers?

18 Shor s Algorithm Factor a number into primes: Conventional M = p * q How long will it take? (t) Quantum Classical Quantum t ~ exp(o(n 1/3 log 2/3 n)) t ~ O(n 3 ) P. W. Shor, Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer," SIAM Journal on Computing, no. 5, p

19 Grover s Algorithm Unsorted database of n items Goal: find one marked item Classically requires order n queries to database needed Grover 1996: Quantum algorithm using order n 1/2 queries

20 Agenda Which problems can not be solved with classical computers? How do quantum computers work? Which problems can be solved with quantum computers? What can we do today with quantum computers?

21 Three challenges to make real quantum computing systems CONTROLLABILITY PRESERVATION SCALABILTY

22 A look at a Quantum Computing Laboratory

23 Inside one of the dilution refrigerators Superconducting materials to obtain controllability Low temperature to obtain preservation

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29 Develop new quantum algorithms Even classical algorithms are very important: from 1988 a problem that would take 82 years would take 1 min in Gain: 1000x from Moore's law (hardware improvements), 43000x from algorithm improvements.

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