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Entanglement types for two-qubit states with real amplitudes

Journal Article · · Quantum Information Processing
 [1];  [2];  [3]
  1. Central Connecticut State Univ., New Britain, CT (United States); Rigetti Computing, Berkeley, CA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computer Science and Engineering Div.
  3. Zapata Computing Canada, Inc., Toronto, ON (Canada); Univ. College London (United Kingdom). Dept. of Computer Science; Rigetti Computing, Berkeley, CA (United States)
We study the set of two-qubit pure states with real amplitudes and their geometrical representation in the three-dimensional sphere. In this representation, we show that the maximally entangled states—those locally equivalent to the Bell states—form two disjoint circles perpendicular to each other. We also show that taking the natural Riemannian metric on the sphere, the set of states connected by local gates are equidistant to this pair of circles. Moreover, the unentangled or so-called product states are π/4 units away to the maximally entangled states. This is, the unentangled states are the farthest away to the maximally entangled states. In this way, if we define two states to be equivalent if they are connected by local gates, we have that there are as many equivalent classes as points in the interval [0,π/4] with the point 0 corresponding to the maximally entangled states. The point π/4 corresponds to the unentangled states which geometrically are described by a torus. Finally, for every 0
Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1777764
Journal Information:
Quantum Information Processing, Journal Name: Quantum Information Processing Journal Issue: 3 Vol. 20; ISSN 1570-0755
Publisher:
SpringerCopyright Statement
Country of Publication:
United States
Language:
English

References (23)

The unknottedness of minimal embeddings journal September 1970
Quantum-state preparation with universal gate decompositions journal March 2011
Absolute maximal entanglement and quantum secret sharing journal November 2012
On Multi-Particle Entanglement journal June 1998
The unknottedness of minimal embeddings journal September 1970
Limited Holism and Real-Vector-Space Quantum Theory journal December 2011
Embedded minimal tori in S3 and the Lawson conjecture journal January 2013
Geometric quantum mechanics journal April 2001
Geometry of Quantum States book January 2006
A generative modeling approach for benchmarking and training shallow quantum circuits journal May 2019
Entanglement monotones journal February 2000
Quantum steering ellipsoids, extremal physical states and monogamy journal August 2014
Exact and asymptotic measures of multipartite pure-state entanglement journal December 2000
Topology of the three-qubit space of entanglement types journal November 2005
Optimal number of controlled-NOT gates to generate a three-qubit state journal March 2008
Quantum-state preparation with universal gate decompositions journal March 2011
Quantum circuits for isometries journal March 2016
Geometry of entanglement in the Bloch sphere journal March 2017
Quantum Steering Ellipsoids journal July 2014
Conditions for a Class of Entanglement Transformations journal July 1999
Synthesis of quantum-logic circuits journal June 2006
An elementary introduction to the geometry of quantum states with pictures journal August 2019
Clifford 3-qubit states journal April 2020

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