Nav: Home

Quantum simulation more stable than expected

April 12, 2019

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. "A particularly promising application is the solution of quantum many-body problems utilizing the concept of digital quantum simulation", says Markus Heyl from Max Planck Institute for the Physics of Complex in Dresden, Germany. "Such simulations could have a major impact on quantum chemistry, materials science and fundamental physics." Within digital quantum simulation the time evolution of the targeted quantum many-body system is realized by a sequence of elementary quantum gates by discretizing time evolution, called Trotterization. "A fundamental challenge, however, is the control of an intrinsic error source, which appears due to this discretization", says Markus Heyl. Together with Peter Zoller from the Department of Experimental Physics at the University of Innsbruck and the Institute of Quantum Optics and Quantum Communication at the Austrian Academy of Sciences and Philipp Hauke from the Kirchhoff Institute for Physics and the Institute for Theoretical Physics at the University of Heidelberg they show in a recent paper in Science Advances that quantum localization-by constraining the time evolution through quantum interference-strongly bounds these errors for local observables.

More robust than expected

"Digital quantum simulation is thus intrinsically much more robust than what one might expect from known error bounds on the global many-body wave function", Heyl summarizes. This robustness is characterized by a sharp threshold as a function of the utilized time granularity measured by the so-called Trotter step size. The threshold separates a regular region with controllable Trotter errors, where the system exhibits localization in the space of eigenstates of the time-evolution operator, from a quantum chaotic regime where errors accumulate quickly rendering the outcome of the quantum simulation unusable. "Our findings show that digital quantum simulation with comparatively large Trotter steps can retain controlled Trotter errors for local observables", says Markus Heyl. "It is thus possible to reduce the number of quantum gate operations required to represent the desired time evolution faithfully, thereby mitigating the effects of imperfect individual gate operations." This brings digital quantum simulation for classically challenging quantum many-body problems within reach for current day quantum devices.
-end-


University of Innsbruck

Related Quantum Articles:

Quantum nanoscope
Researchers have studied how light can be used to 'see' the quantum nature of an electronic material.
'Quantum leap' for Liverpool
Physicists from the University of Liverpool have made a huge step forwards towards building a novel experiment to probe the 'dark contents' of the vacuum.
Testing quantum field theory in a quantum simulator
Quantum field theories are often hard to verify in experiments.
Quantum reservoir for microwaves
EPFL researchers use a mechanical micrometer-size drum cooled close to the quantum ground state to amplify microwaves in a superconducting circuit.
Looking for the quantum frontier
Researchers have developed a new theoretical framework to identify computations that occupy the 'quantum frontier' -- the boundary at which problems become impossible for today's computers and can only be solved by a quantum computer.
Quantum mechanics are complex enough, for now...
Physicists have searched for deviations from standard quantum mechanics, testing whether quantum mechanics requires a more complex set of mathematical rules.
Seeing the quantum future... literally
Sydney scientists have demonstrated the ability to 'see' the future of quantum systems and used that knowledge to preempt their demise, in a major achievement that could help bring the strange and powerful world of quantum technology closer to reality.
The sound of quantum vacuum
Quantum mechanics dictates sensitivity limits in the measurements of displacement, velocity and acceleration.
New quantum states for better quantum memories
How can quantum information be stored as long as possible?
Watching quantum jumps
When a quantum system changes its state, this is called a quantum jump.

Related Quantum Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".