Barbara Terhal

Last updated
Barbara M. Terhal
Born1969 (age 53–54)
Leiden, Netherlands [1]
Alma mater University of Amsterdam
Known for
Spouse David DiVincenzo [ citation needed ]
Scientific career
Fields Physics (theoretical)
Institutions
Doctoral students Nikolas Breuckmann

Barbara M. Terhal (born 1969) is a theoretical physicist working in quantum information and quantum computing. She is a professor in the Delft Institute of Applied Mathematics at TU Delft, as well as leading the Terhal Group at QuTech, the Dutch institute for quantum computing and quantum internet, founded by TU Delft and the Netherlands Organisation for Applied Scientific Research (TNO). Her research concerns many areas in quantum information theory, including entanglement detection, quantum error correction, fault-tolerant quantum computing and quantum memories.

Contents

Education and early life

Barbara Terhal was born in Leiden in 1969. [2] Already in her early school days, she enjoyed mathematics, physics and solving puzzles. [3]

Terhal completed her PhD Cum Laude on "Quantum Algorithms and Quantum Entanglement" [4] at the University of Amsterdam in 1999, making her the first person to receive a PhD in quantum computing in the Netherlands. [5] As part of her thesis, she coined the term entanglement witness [4] [6] and proposed their use as alternatives to Bell tests for entanglement detection.

Career and research

After her PhD, Terhal joined the IBM Watson Research Centre in Yorktown Heights, New York [7] and the California Institute of Technology (Caltech) as a postdoctoral researcher. Between 2001 and 2010, she worked at IBM on a number of topics, including low-depth quantum circuits or stoquastic Hamiltonians, perturbative gadgets for quantum simulation and quantum complexity theory. She also developed quantum protocols for remote state preparation, quantum locking and quantum data hiding. [5]

In 2010, Terhal became a professor in theoretical physics at RWTH Aachen University. In addition, she held another position at the Forschungszentrum Jülich from 2015 - 2022. [8] In 2017 she moved to Delft, becoming a professor at the Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS) at TU Delft and group leader at QuTech. [7]

Since 2007, Terhal has been a fellow of the American Physical Society and has held the post of Distinguished Visiting Research Chair at the Perimeter Institute in Waterloo, Canada, since 2014. [9]

Terhal's current research focuses on quantum error correction and its realisation in solid-state qubits. [3] She is also interested in quantum complexity theory and how it can be used to demonstrate the power of a quantum computer. [3]

Awards

Barbara Terhal has received the following awards:

Publications

Her publications include:

She has also written an essay on the fragility of quantum information. [16]

Related Research Articles

In physics, the no-cloning theorem states that it is impossible to create an independent and identical copy of an arbitrary unknown quantum state, a statement which has profound implications in the field of quantum computing among others. The theorem is an evolution of the 1970 no-go theorem authored by James Park, in which he demonstrates that a non-disturbing measurement scheme which is both simple and perfect cannot exist. The aforementioned theorems do not preclude the state of one system becoming entangled with the state of another as cloning specifically refers to the creation of a separable state with identical factors. For example, one might use the controlled NOT gate and the Walsh–Hadamard gate to entangle two qubits without violating the no-cloning theorem as no well-defined state may be defined in terms of a subsystem of an entangled state. The no-cloning theorem concerns only pure states whereas the generalized statement regarding mixed states is known as the no-broadcast theorem.

<span class="mw-page-title-main">Quantum entanglement</span> Correlation between quantum systems

Quantum entanglement is the phenomenon that occurs when a group of particles are generated, interact, or share spatial proximity in such a way that the quantum state of each particle of the group cannot be described independently of the state of the others, including when the particles are separated by a large distance. The topic of quantum entanglement is at the heart of the disparity between classical and quantum physics: entanglement is a primary feature of quantum mechanics not present in classical mechanics.

In quantum mechanics, einselections, short for "environment-induced superselection", is a name coined by Wojciech H. Zurek for a process which is claimed to explain the appearance of wavefunction collapse and the emergence of classical descriptions of reality from quantum descriptions. In this approach, classicality is described as an emergent property induced in open quantum systems by their environments. Due to the interaction with the environment, the vast majority of states in the Hilbert space of a quantum open system become highly unstable due to entangling interaction with the environment, which in effect monitors selected observables of the system. After a decoherence time, which for macroscopic objects is typically many orders of magnitude shorter than any other dynamical timescale, a generic quantum state decays into an uncertain state which can be expressed as a mixture of simple pointer states. In this way the environment induces effective superselection rules. Thus, einselection precludes stable existence of pure superpositions of pointer states. These 'pointer states' are stable despite environmental interaction. The einselected states lack coherence, and therefore do not exhibit the quantum behaviours of entanglement and superposition.

The Peres–Horodecki criterion is a necessary condition, for the joint density matrix of two quantum mechanical systems and , to be separable. It is also called the PPT criterion, for positive partial transpose. In the 2×2 and 2×3 dimensional cases the condition is also sufficient. It is used to decide the separability of mixed states, where the Schmidt decomposition does not apply. The theorem was discovered in 1996 by Asher Peres and the Horodecki family

In quantum mechanics, separable states are multipartite quantum states that can be written as a convex combination of product states. Product states are multipartite quantum states that can be written as a tensor product of states in each space. The physical intuition behind these definitions is that product states have no correlation between the different degrees of freedom, while separable states might have correlations, but all such correlations can be explained as due to a classical random variable, as opposed as being due to entanglement.

In quantum information theory, an entanglement witness is a functional which distinguishes a specific entangled state from separable ones. Entanglement witnesses can be linear or nonlinear functionals of the density matrix. If linear, then they can also be viewed as observables for which the expectation value of the entangled state is strictly outside the range of possible expectation values of any separable state.

Squashed entanglement, also called CMI entanglement, is an information theoretic measure of quantum entanglement for a bipartite quantum system. If is the density matrix of a system composed of two subsystems and , then the CMI entanglement of system is defined by

Quantum cloning is a process that takes an arbitrary, unknown quantum state and makes an exact copy without altering the original state in any way. Quantum cloning is forbidden by the laws of quantum mechanics as shown by the no cloning theorem, which states that there is no operation for cloning any arbitrary state perfectly. In Dirac notation, the process of quantum cloning is described by:

In the case of systems composed of subsystems, the classification of quantum-entangledstates is richer than in the bipartite case. Indeed, in multipartite entanglement apart from fully separable states and fully entangled states, there also exists the notion of partially separable states.

Michał Horodecki is a Polish physicist at the University of Gdańsk working in the field of quantum information theory, notable for his work on entanglement theory.

In quantum computing, the threshold theorem states that a quantum computer with a physical error rate below a certain threshold can, through application of quantum error correction schemes, suppress the logical error rate to arbitrarily low levels. This shows that quantum computers can be made fault-tolerant, as an analogue to von Neumann's threshold theorem for classical computation. This result was proven by the groups of Dorit Aharanov and Michael Ben-Or; Emanuel Knill, Raymond Laflamme, and Wojciech Zurek; and Alexei Kitaev independently. These results built off a paper of Peter Shor, which proved a weaker version of the threshold theorem.

Dipankar Home is an Indian theoretical physicist at Bose Institute, Kolkata. He works on the fundamental aspects of quantum mechanics, including quantum entanglement and Quantum communication. He is co-author with Partha Ghose of the popular book Riddles in your Teacup - Fun with Everyday Scientific Puzzles.

Paweł Horodecki is a Polish professor of physics at the Gdańsk University of Technology working in the field of quantum information theory. He is best known for introducing the Peres-Horodecki criterion for testing whether a quantum state is entangled. Moreover, Paweł Horodecki demonstrated that there exist states which are entangled whereas no pure entangled states can be obtained from them by means of local operations and classical communication (LOCC). Such states are called bound entangled states. He also showed that even bound entanglement can lead to quantum teleportation with a fidelity impossible to achieve with only separable states.

In quantum information theory, quantum discord is a measure of nonclassical correlations between two subsystems of a quantum system. It includes correlations that are due to quantum physical effects but do not necessarily involve quantum entanglement.

Ryszard Horodecki is a Polish physicist and a professor of University of Gdańsk. He contributed largely to the field of quantum informatics. In his most widely cited paper, 'Separability of Mixed States: Necessary and Sufficient Conditions' written together with his sons, Michał and Paweł, he proposed the idea currently known as the Peres-Horodecki criterion. With over 12,000 citations, he is considered to be one of the leading Polish physicists.

<span class="mw-page-title-main">Julia Kempe</span> French, German, and Israeli researcher in quantum computing

Julia Kempe is a French, German, and Israeli researcher in quantum computing. She is currently the Director of the Center for Data Science at NYU and Professor at the Courant Institute.

<span class="mw-page-title-main">Ronald Hanson</span> Dutch physicist

Ronald Hanson is a Dutch experimental physicist. He is best known for his work on the foundations and applications of quantum entanglement. He is Antoni van Leeuwenhoek Professor at the Kavli Institute of Nanoscience at Delft University of Technology and scientific director of QuTech. the Dutch Quantum Institute for quantum computing and quantum internet, founded by Delft University of Technology and the Netherlands Organisation for Applied Research.

Barbara Kraus ) is an Austrian physicist specializing in quantum information, quantum entanglement, and quantum key distribution. She is a University Professor at the TUM School of Natural Sciences at the Technical University of Munich.

Bound entanglement is a weak form of quantum entanglement, from which no singlets can be distilled with local operations and classical communication (LOCC).

This glossary of quantum computing is a list of definitions of terms and concepts used in quantum computing, its sub-disciplines, and related fields.

References

  1. ↑ "Barbara-M-Terhal". RWTH Aachen Research Group. Archived from the original on 6 April 2018. Retrieved 28 July 2016.
  2. ↑ "Barbara Terhal". QuTech. Retrieved 2018-12-09.
  3. 1 2 3 "Six Questions with: Professor Barbara Terhal". Isaac Newton Institute for Mathematical Sciences. Archived from the original on 10 December 2018. Retrieved 9 December 2018.
  4. 1 2 Terhal, Barbara M. (2000). "Bell inequalities and the separability criterion". Physics Letters A. 271 (5–6): 319–326. arXiv: quant-ph/9911057 . Bibcode:2000PhLA..271..319T. doi:10.1016/S0375-9601(00)00401-1. S2CID   14295118.
  5. 1 2 "Terhal Group - QuTech". QuTech. Retrieved 2018-10-19.
  6. ↑ "Physicists Find a Way to See the 'Grin' of Quantum Gravity | Quanta Magazine". Quanta Magazine. Retrieved 2018-10-19.
  7. 1 2 "Barbara M. Terhal - RWTH AACHEN UNIVERSITY Institute for Quantum Information - English". www.quantuminfo.physik.rwth-aachen.de. Archived from the original on 2018-06-12. Retrieved 2018-12-09.
  8. ↑ "Barbara Terhal". QuTech. Retrieved 2023-10-20.
  9. ↑ "Barbara Terhal". www.online-learning.tudelft.nl/. Retrieved 2020-07-02.
  10. 1 2 "Awards - RWTH AACHEN UNIVERSITY Institute for Quantum Information - English". www.quantuminfo.physik.rwth-aachen.de. Retrieved 2018-12-09.
  11. ↑ "Physical Review Journals - Outstanding Referees". journals.aps.org. Retrieved 2018-12-09.
  12. ↑ "Barbara Terhal". Royal Netherlands Academy of Arts and Sciences. Archived from the original on 2 May 2020.
  13. ↑ Terhal, Barbara M. (2000-07-10). "Bell inequalities and the separability criterion". Physics Letters A. 271 (5–6): 319–326. arXiv: quant-ph/9911057 . Bibcode:2000PhLA..271..319T. CiteSeerX   10.1.1.251.5437 . doi:10.1016/S0375-9601(00)00401-1. ISSN   0375-9601. S2CID   14295118.
  14. ↑ Terhal, Barbara M.; DiVincenzo, David P. (2002-05-21). "Adaptive Quantum Computation, Constant Depth Quantum Circuits and Arthur-Merlin Games". arXiv: quant-ph/0205133 . Bibcode:2002quant.ph..5133T.{{cite journal}}: Cite journal requires |journal= (help)
  15. ↑ Terhal, Barbara M. (2015-04-07). "Quantum error correction for quantum memories". Reviews of Modern Physics. 87 (2): 307–346. arXiv: 1302.3428 . Bibcode:2015RvMP...87..307T. doi:10.1103/RevModPhys.87.307. S2CID   118646257.
  16. ↑ Terhal, Barbara M. (2013-05-17). "The Fragility of Quantum Information?". arXiv: 1305.4004 [quant-ph].
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