scalable quantum computing with superconducting qubits · pdf filewalter riess ibm research...
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Walter Riess
IBM Research – Zurich
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
© 2017 International Business Machines Corporation
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
© 2017 International Business Machines Corporation
+
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
© 2017 International Business Machines Corporation
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)
© 2017 International Business Machines Corporation
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.
© 2017 International Business Machines Corporation
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
© 2017 International Business Machines Corporation
Roadmap: Quantum Systems complement classical Systems
A small quantum computer is combined with a classical
computer to jointly solve a computational task.
© 2017 International Business Machines Corporation
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
© 2017 International Business Machines Corporation
𝐇𝟐: 2 qubits
5 pauli terms, 2 sets
LiH: 4 qubits
100 pauli terms, 25 sets
𝐁𝐞𝐇𝟐: 6 qubits
144 pauli terms, 36 sets
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.
© 2017 International Business Machines Corporation
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
© 2017 International Business Machines Corporation
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