Scalable Quantum Computing with Superconducting Qubits · PDF fileWalter Riess IBM Research...

Walter Riess

IBM Research – Zurich

[email protected]

Scalable Quantum Computing with

Superconducting Qubits

© 2017 International Business Machines Corporation

3D / hybrid

Cognitive (neuromorphic)

Computing

Quantum Computing

First integrated circuit

Size ~1cm2

2 Transistors

Moore’s Law is Born

Intel 4004

2,300 transistors

IBM P8 Processor ~ 650 mm2

22 nm feature size, 16 cores

> 4.2 Billion Transistors

1958 1971 2014Next Generation Systems

The Future of Computing – An industry perspective


Easy Problems

13 x 7 = ?

937 x 947 = ?

Hard Problems for

Classical Computing

Possible with

Quantum Computing

Materials &

Drug discovery

Machine

Learning

Searching

Big Data

Many problems in business and science are too complex for classical computing systems

“hard” / intractable problems:

(exponentially increasing resources with problem size)

• Algebraic algorithms (e.g. factoring, systems of equations)

for machine learning, cryptography,…

• Combinatorial optimization (traveling salesman,

optimizing business processes)

• Simulating quantum mechanics (chemistry, material science,…)

91 = ? x ?

887339 = ? x ?

Quantum Computing as a path to solve intractable problems

Superconducting Qubit Processor – A Closer Look

Microwave Resonator as: read-out of qubit states

multi-qubit quantum bus

noise filter

Superconducting Qubit: non-linear Josephson Junction (Inductance)

anharmonic energy spectrum => qubit

nearly dissipationless => T1, T2 ~ 70 µs


+

Chip with superconductingqubits and resonators

PCB with the qubit chip at 20mKProtected from the environment by multiple shields

2.7K

0.8K

0.1K

0.02KMicrowave electronics

Dilution cryostat

-270℃

|1⟩|0⟩

The Superconducting Quantum Computing Setup


4 Qubits (2015)

8 Qubits (2016)

05/2016: 5 Qubits hosted on IBM Quantum Experience05/2017: 16 Qubits on Quantum Experience, 17 Qubits on IBMQ (commercial)

Latticed arrangement for scaling

5 Qubits (2016)

16 Qubits (2017)


Quantum Volume

Number of qubits (more is better)

Errors (less is better)

Connectivity (more is better)

Gates set (more is better)

How powerful is “my” Quantum Computer

The quantum volume

measures the useful amount

of quantum computing done

by a device in space and time.


reaction rates reaction pathwaysmolecular structure

Sign problem: Monte-Carlo simulations of fermions are NP-hard[Troyer &Wiese, PRL 170201 (2015)]

Solving interacting fermionic problems is at the core of most challenges in computational physics and

high-performance computing:

What can quantum computers do?

Map fermions (electrons) to qubits and compute

Quantum optimization for chemistry

𝐻𝑒 = −

𝑖=1

𝑁1

2𝛻𝑖2 −

𝑖=1

𝑁

𝐴=1

𝑀𝑍𝐴𝑟𝑖𝐴+

𝑗>1

1

𝑟𝑖𝑗


Roadmap: Quantum Systems complement classical Systems

A small quantum computer is combined with a classical

computer to jointly solve a computational task.


High level approach: hybrid quantum-classical algorithms

Advantages:

Use short circuits which fit into our coherence time

Improve on best classical estimates by using non-classical trial states

A simple hybrid quantum-classical algorithm can be used to solve problems where the

goal is to minimize the energy of a system.

Prepare a trial state 𝜓 𝜃and compute its energy 𝐸(𝜃) Use classical optimizer to choose

a new value of 𝜃 to try


𝐇𝟐: 2 qubits

5 pauli terms, 2 sets

LiH: 4 qubits


𝐁𝐞𝐇𝟐: 6 qubits


Groundstate-energy of simple molecules

Hardware-efficient variational quantum eigensolver for small molecules and quantum magnets

Abhinav Kandala1*, Antonio Mezzacapo1*, Kristan Temme1, Maika Takita1, Markus Brink1, Jerry M. Chow1 & Jay M. Gambetta1,

doi:10.1038/nature23879

Using six qubits of a seven-qubit processor it was able to

measure BeH2’s lowest energy state, a key measurement for

understanding chemical reactions. While this model of

BeH2 can be simulated on a classical computer, IBM’s

approach has the potential to scale towards investigating larger

molecules that would traditionally be seen to be beyond the

scope of classical computational methods, as more powerful

quantum systems get built.


Goal:

Build computers based on quantum physics to solve problems that are otherwise intractable

Develop “Hardware-efficient” apps

− Chemical configurations

− Simple Optimization

− Hybrid quantum-classical computers

No full error correction available

5-8 qubits 16-20 qubits 50-100+ qubits 105-106 qubits

Small-scale (Quantum advantage) Medium-scale (approximate QC) Large-scale (Universal QC)

Research level demonstrations

Verify chemistry and error correction

principles

Infrastructure & community building

Demonstrate ‘Quantum advantage’

Known and proven speed-up:

Factoring

quantum molecular simulations

Machine learning, optimization

Enable secure cloud computing

Roadmap:

Challenges: Continued scalability, control and coherence of large systems,…

Grand Challenge: Quantum Computing

Control Software

Cryogenics and Control Electronics

System Characterization

Fabrication/3D Integration

Microwave circuit design

& Quantization

Numerical High

Frequency SimulationSystem Simulation

Superconducting Quantum Processor

can be engineered

builds on existing technologies

challenges in coherence, control

complexity and scaling

Quantum Algorithms

The Quantum Eco System


Ways you can engage IBM with Quantum

Early access to IBM Q System

https://www.research.ibm.com/ibm-q/

Partner to Develop

Quantum Applications

Public usage of the IBM Q

experience

https://www.research.ibm.com/ibm-q/

IBM Research

Frontiers Institute

https://www.ibm.com/research/

frontiers

Independent experimentation

and learning

World’s most advanced

hardware

November 7, 2017

IBM Quantum Computing European Workshop

A one-day event held at IBM Research – Zurich

Factoring and therefore encryption breaking using current schemes will not

be a significant application of quantum computing for many years.

By the time we can do this, we will have changed our encryption

algorithms (PQC).

But this doesn’t mean one should do nothing!

If you have data which needs to be safe decades from now you can already

begin to make it quantum safe……

Threats to Cryptography

Thank you for your attention!

Walter [email protected] Research - Zurich

Scalable Quantum Computing with Superconducting Qubits · PDF fileWalter Riess IBM Research...

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