## Profile1999-2003, BS. Physics, University of Bucharest, Romania
2004-2006, MS. Physics, Carnegie Mellon University, Pittsburgh PA, USA
2006-2010, PhD. Physics (Quantum Information Theory), Carnegie Mellon University, Pittsburgh PA, USA
2010-2011, Research Associate, Carnegie Mellon University, Pittsburgh PA, USA
2011-2013, PIMS Postdoctoral Fellow, Institute for Quantum Information Science and Department of Mathematics and Statistics, University of Calgary, Calgary AB, Canada
Multipartite Entanglement and Quantum Correlations
Quantum Error Correction
Hybrid classical/quantum protocols
Quantum Communication Complexity
Additivity of the Quantum Channel Capacity ## Outputs
Title | Category | Date | Authors |
Entanglement transformations using separable operations University of Calgary | Publication | 2007-09-01 | V. Gheorghiu, R. B. Griffiths | Separable operations on pure states University of Calgary | Publication | 2008-08-01 | V. Gheorghiu, R. B. Griffiths | Location of quantum information in additive graph codes University of Calgary | Publication | 2010-03-01 | V. Gheorghiu, S. Y. Looi, R. B. Griffiths | Multipartite entanglement evolution under separable operations University of Calgary, University of California, San Diego | Publication | 2012-11-01 | V. Gheorghiu, G. Gour | Accessing quantum secrets via local operations and classical communication University of Calgary | Publication | 2013-01-01 | V. Gheorghiu, B. C. Sanders | Generalized semiquantum secret-sharing schemes University of Calgary | Publication | 2012-05-01 | V. Gheorghiu | Information-theoretical study of collisional decoherence of chiral molecules in a gas University of Calgary | Presentation | 2011-05-10 | V. Gheorghiu | Optimal semi-quantum secret sharing schemesI will introduce the notion of stabilizer quantum error correcting codes and perfect quantum secret sharing schemes. Then I will illustrate how, using any given stabilizer code, one can always construct a perfect quantum secret sharing scheme out of it by allowing the sharing of extra classical bits between the dealer and the players.Next I will describe a general scheme of reducing the amount of classical communication, then prove that the scheme is optimal for the stabilizer code being used.The optimality proof is based on the fact that the correlations between the dealer and the players can be fully described by an "information" group, a subgroup of the symplectic Weil-Heisenberg group. The symplectic structureof the information group effectively gives the minimum number of classical bits required. Finally I will provide an explicit protocol that achieves the bound by employingthe notion of "twirling" (or scrambling) the information group.The talk will be self-contained and no prior exposure to quantum information is assumed. Most ideas will be illustrated by simple examples. University of Calgary | Presentation | 2012-02-07 | V. Gheorghiu | Optimal perfect quantum secret sharing schemes via stabilizer quantum error correcting codes and I will introduce the notion of stabilizer quantum error correcting codes and perfect quantum secret sharing schemes, then I will illustrate how, using any given stabilizer code, one can always construct a perfect quantum secret sharing scheme out of it by allowing the sharing of extra classical bits between the dealer and the players.
Next I will describe a general scheme of reducing the amount of classical communication, then prove that the scheme is optimal for the stabilizer code being used. The optimality proof is based on the fact that the correlations between the dealer and the players can be fully described by an ``information" group, a subgroup of the symplectic Weil-Heisenberg group; the symplectic structure of the information group effectively gives the minimum number of classical bits required. Finally I will provide an explicit protocol that achieves the bound by employing the notion of ``twirling" (or scrambling) the information group.
The talk will be self-contained and no prior exposure to quantum error correcting theory is assumed. Most ideas will be illustrated by simple examples. University of Calgary | Presentation | 2012-02-08 | V. Gheorghiu | Recovering quantum secrets via classical channelsQuantum secret sharing is an important multipartite cryptographic protocol in which a quantum state (secret) is shared among a set of n players. The secret is distributed in such a way that it can only be recovered by certain authorized subsets of players acting collaboratively. The recovery procedure assumes that all players are interconnected through quantum channels, or, equivalently, that the players are allowed to perform non-local quantum operations. However, for practical applications, the consumption of quantum communication resources such as entanglement or quantum channels needs to minimized.
We provide a novel scheme in which quantum communication is replaced by local operations and classical communication (LOCC). Our protocol is based on embedding a classical maximum distance separable (MDS) code into a quantum error correcting code and employing the properties of the latter. Our scheme is appealing for real-world scenarios where the implementation of two-qubit gates is challenging. We illustrate the results by simple examples. Our methods constitute a first step towards attacking the important problem of decoding quantum error correcting codes by LOCC.
*Collaboration with Barry C. Sanders.
We acknowledge support from the Natural Sciences and Engineering Research Council (NSERC) of Canada and from Paciﬁc Institute for Mathematical Sciences (PIMS).
University of Calgary | Presentation | 2013-02-21 | V. Gheorghiu, B. C. Sanders | Recovering quantum information via classical channelsQuantum secret sharing is an important multipartite cryptographic protocol in which a quantum state\r\n(secret) is shared among a set of n players. The secret is distributed in such a way that it can only be\r\nrecovered by certain authorized subsets of players acting collaboratively. The recovery procedure assumes\r\nthat all players are interconnected through quantum channels, or, equivalently, that the players are allowed\r\nto perform non-local quantum operations. However, for practical applications, the consumption of quantum\r\ncommunication resources such as entanglement or quantum channels needs to minimized.\r\nWe provide a novel scheme in which quantum communication is replaced by local operations and classical\r\ncommunication (LOCC). Our protocol is based on embedding a classical maximum distance separable (MDS)\r\ncode into a quantum error correcting code and employing the properties of the latter. Our scheme is appealing\r\nfor real-world scenarios where the implementation of two-qubit gates is challenging. We illustrate the results\r\nby simple examples. Our methods constitute a rst step towards attacking the important problem of decoding\r\nquantum error correcting codes by LOCC. University of Calgary | Presentation | 2013-02-26 | V. Gheorghiu, B. C. Sanders | Optimal semi-quantum secret sharing schemes via stabilizer codes and twirling of symplectic structuresAs recently shown in [quant-ph/1108.5541], any quantum error-correcting code can be converted into a perfect "hybrid" quantum secret sharing scheme by allowing the sharing of extra classical bits between the dealer and the players. An advantage of this scheme is that it allows the players' quantum shares to be of smaller dimension than the dimension of the encoded secret, which is impossible for regular perfect quantum secret sharing protocols. Whenever the underlying quantum error correcting code is a stabilizer code (this being the case for the vast majority of known quantum error-correcting codes), I provide a general scheme of reducing the amount of classical communication required, then prove that my scheme is optimal for the stabilizer code being used. The optimality proof is based on the fact that the correlations between the dealer and the players can be fully described by an "information group" [Phys. Rev. A 81, 032326 (2010)]; the symplectic structure of the information group effectively gives the minimum number of classical bits required. Finally I provide an explicit protocol that achieves this minimum by employing the notion of "twirling" (or scrambling) the information group. The results are general and valid for any stabilizer code. I will illustrate the results by simple examples. University of Calgary | Presentation | 2012-02-18 | V. Gheorghiu | Quantum entanglement: properties and evolutionEntanglement is a key ingredient in a quantum computer, allowing for quantum
algorithms that perform exponentially faster than any classical counterpart, such
as factoring large numbers. In this talk I will gently introduce the concept of entanglement as a notion of quantum correlations and discuss some of its properties. I will then show how to explicitly quantify the ``decay" of entanglement due
external noise during a physical process (aka decoherence). The talk is intended
to be self-contained and no prior exposure to quantum mechanics is required. University of Calgary | Presentation | 2012-05-04 | V. Gheorghiu, G. Gour | Nonzero classical discord University of Calgary | Publication | 2015-01-01 | V. Gheorghiu, M. C. De, B. C. Sanders | Consistent histories for tunneling molecules subject to collisional decoherence University of Calgary | Publication | 2012-10-01 | P. J. Coles, V. Gheorghiu, R. B. Griffiths | Universal Uncertainty Relations University of Calgary | Publication | 2013-12-01 | S. Friedland, V. Gheorghiu, G. Gour | Collisional decoherence of tunneling molecules: a consistent histories treatment University of Calgary | Publication | 2012-01-01 | P. J. Coles, V. Gheorghiu, R. B. Griffiths | Universal uncertainty relationsUncertainty relations lie at the core of quantum mechanics and are a direct manifestation of the non-commutative structure of the theory. They impose intrinsic limitations on the precision with which physical properties can be simultaneously determined. The modern work on uncertainty relations employs \\emph{entropic measures} to quantify the lack of knowledge associated with measuring non-commuting observables. However there is no fundamental reason for using entropies as quantifiers; any functional relation that characterizes the uncertainty of the measurement outcomes defines an uncertainty relation. Starting from a simple requirement any reasonable measure of uncertainty has to satisfy, we show that Schur-concave functions are the most general uncertainty quantifiers. We then discover a novel fine-grained uncertainty relation written in terms of a majorization relation, which generates an infinite family of distinct scalar uncertainty relations via the application of uncertainty quantifiers. Our relation is universally valid and captures the essence of uncertainty in quantum mechanics. University of Calgary, University of California, San Diego | Presentation | 2013-03-06 | S. Friedland, V. Gheorghiu, G. Gour | Universal uncertainty relationsUncertainty relations lie at the core of quantum mechanics and are a direct manifestation of the non-commutative structure of the theory. They impose intrinsic limitations on the precision with which physical properties can be simultaneously determined. The modern work on uncertainty relations employs *entropic measures* to quantify the lack of knowledge associated with measuring non-commuting observables. However there is no fundamental reason for using entropies as quantifiers; any functional relation that characterizes the uncertainty of the measurement outcomes defines an uncertainty relation. Starting from a simple requirement any reasonable measure of uncertainty has to satisfy, we show that Schur-concave functions are the most general uncertainty quantifiers. We then discover a novel fine-grained uncertainty relation written in terms of a majorization relation, which generates an infinite family of distinct scalar uncertainty relations via the application of uncertainty quantifiers. Our relation is universally valid and captures the essence of uncertainty in quantum mechanics. University of Calgary, University of California, San Diego | Presentation | 2013-03-20 | S. Friedland, V. Gheorghiu, G. Gour | Universal uncertainty relationsUncertainty relations lie at the core of quantum mechanics and are a direct manifestation of the non-commutative structure of the theory. They impose intrinsic limitations on the precision with which physical properties can be simultaneously determined. The modern work on uncertainty relations employs \\emph{entropic measures} to quantify the lack of knowledge associated with measuring non-commuting observables. However there is no fundamental reason for using entropies as quantifiers; any functional relation that characterizes the uncertainty of the measurement outcomes defines an uncertainty relation. Starting from a simple requirement any reasonable measure of uncertainty has to satisfy, we show that Schur-concave functions are the most general uncertainty quantifiers. We then discover a novel fine-grained uncertainty relation written in terms of a majorization relation, which generates an infinite family of distinct scalar uncertainty relations via the application of uncertainty quantifiers. Our relation is universally valid and captures the essence of uncertainty in quantum mechanics.\r\n\r\nThis work is in collaboration with Gilad Gour (IQST) and Shmuel Friedland (Univ. of Illinois at Chicago). The talk will be self contained and no prior exposure to quantum mechanics is required. University of Calgary, University of California, San Diego | Presentation | 2013-03-21 | S. Friedland, V. Gheorghiu, G. Gour | Universal Uncertainty Relations University of Calgary | Publication | 2013-12-01 | S. Friedland, V. Gheorghiu, G. Gour | On the robustness of bucket brigade quantum RAM University of Calgary | Publication | 2015-01-01 | S. Arunachalam, V. Gheorghiu, T. Jochym-OâConnor, M. Mosca, P. Srinivasan | Quantum-error-correcting codes using qudit graph states University of Calgary | Publication | 2008-10-01 | S. Y. Looi, L. Yu, V. Gheorghiu, R. B. Griffiths | Information-theoretic treatment of tripartite systems and quantum channels University of Calgary | Publication | 2011-06-01 | P. J. Coles, L. Yu, V. Gheorghiu, R. B. Griffiths |
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