A many-body quantum system

Subsystem symmetry enabling quantum computation

Austin Daniel, Rafael Alexander, and Akimasa Miyake have published a paper in the journal Quantum demonstrating that certain many-body quantum systems, when placed on lattices with different geometries, can possess a variety of exotic “subsystem symmetries” that can be utilized to empower quantum computation. 

It has long been an open problem to understand which quantum many-body states are useful for measurement-based quantum computing (MBQC), a scheme whereby local measurements on a large, entangled quantum state drive a computational process. 

In the past, it was suggested that such systems should possess special topological properties with respect to a symmetry, known as symmetry protected topological order (SPTO).

Traditionally, these many-body systems were studied in terms of a global symmetry that acts uniformly on every site in the lattice; however, recent work has highlighted the importance of subsystem symmetries, which act on special subsets of the lattice. 

The authors show that for a variety of lattices there are large families of many-body systems that posses a common subsystem SPTO, ensuring that any such system is a resource for MBQC. 

This demonstrates that resources for MBQC extend far beyond what was previously known. 

The full article can be found online at https://quantum-journal.org/papers/q-2020-02-10-228/ .

An example of a subsystem symmetry that protects the cluster-phase on the (3,4,6,4) Archimedean lattice.

 

UNM to participate in $15 million NSF program to create first practical quantum computer

 

 

 

 

 

 

 

 

 

 

 

 

 

 
A research team of the University of New Mexico led by CQuIC faculty, Akimasa Miyake, will participate in a $15 million, multi-university collaboration as part of a National Science Foundation program designed with the audacious goal of building the world’s first practical quantum computer. Read the UNM news article.

 
Team of STAQ-project researchers at Ideas Lab meeting at the Santa Fe Institute in Fall 2017. Front row (l. to r.): Hartmut Haeffner (University of California, Berkeley), Aram Harrow (Massachusetts Institute of Technology), and Kenneth Brown (Duke University). Back row l. to r.): Akimasa Miyake (University of New Mexico), Alexey Gorshkov (University of Maryland College Park), Jungsang Kim (Duke University), Peter Love (Tufts University), Christopher Monroe (University of Maryland College Park), and Frederic Chong (University of Chicago).

Symmetric Phases of Universal Quantum Computation

Jacob Miller and Akimasa Miyake have recently published a paper in Physical Review Letters giving strong evidence that certain forms of symmetric topological quantum matter can be utilized ubiquitously to power quantum computation. Their work is carried out within measurement-based quantum computation, where computation is extracted from a fixed quantum “resource state” using local measurements. In this setting, the power of computation attributes the physical properties of the resource state, but the properties which guarantee a state can carry out universal quantum computation are still unknown.
In their work, the authors study a model of symmetric topological matter and identify special states in each phase which enable universal quantum computation precisely when they possess nontrivial quantum order. This gives an infinite family of new universal resource states whose structure perfectly mirrors a recent classification of symmetric quantum order coming from condensed matter physics. These special resource states are distinguished by their “fractional symmetry”, a property already noticed in previous universal resource states, but which hadn’t been investigated systematically. Overall, the work provides a concrete research program for identifying phases of universal quantum computation within the setting of symmetric quantum matter.
The full article can be found online at Phys. Rev. Lett. 120, 170503 (2018).
Classification of special resource states with fractional symmetry.

Chair’s Award of Best Dissertation in Physics

Jacob Miller completed his PhD under Akimasa Miyake about a year ago, with a dissertation entitled Measurement-Based Quantum Computation and Symmetry-Protected Topological Order.  In his thesis, Jacob made fundamental contributions to understanding the kind of many-body entanglement that can enable universal quantum computation within the framework of measurement-based quantum computation.  CQuIC’ers were reminded of Jacob’s outstanding research at the 2018 Physics and Astronomy Convocation on May 12, when he was awarded the Chair’s Award for Best Dissertation in Physics for the preceding year.   Notable not just for outstanding research, Jacob’s dissertation also contained a full-page paean to CQuIC’s TACLA Coffee Club, for which Jacob was Coffee Commander for several years.  Recognizing fully the mutual relationship between coffee and research, Jacob wrote: “For there is no question that in the face of tough research puzzles, prickly conundrums, and flummoxes of every type, we can find solace in the words of noted abolitionist Henry Ward Beecher that, `A cup of coffee—real coffee—homebrowned, home ground, home made, that comes to you dark as a hazel-eye . . .  neither lumpy nor frothing on the Java: such a cup of coffee is a match for twenty blue devils and will exorcise them all.’ ’’