Quantum Process Tomography by Direct Characterization of Quantum Dynamics Using Hyperentangled Photons

2010 ◽  
Author(s):  
Trent Graham ◽  
Julio Barreiro ◽  
Paul G. Kwiat
Keyword(s):  
Quantum Dynamics ◽  
Quantum Process ◽  
Quantum Process Tomography ◽  
Process Tomography

scholarly journals Characterization of depolarizing channels using two-photon interference

2019 ◽  
Vol 18 (11) ◽  
Author(s):  
G. C. Amaral ◽  
G. P. Temporão
Keyword(s):  
Quantum Communication ◽  
Communication Link ◽  
Time Varying ◽  
Quantum Process ◽  
Standard Quantum ◽  
Two Photon ◽  
Quantum Process Tomography ◽  
Process Tomography ◽  
Unitary Transformations

Abstract Depolarization is one of the most important sources of error in a quantum communication link that can be introduced by the quantum channel. Even though standard quantum process tomography can, in theory, be applied to characterize this effect, in most real-world implementations depolarization cannot be distinguished from time-varying unitary transformations, especially when the timescales are much shorter than the detectors response time. In this paper, we introduce a method for distinguishing true depolarization from fast polarization rotations by employing Hong–Ou–Mandel interference. It is shown that the results are independent of the timing resolutions of the photodetectors.

scholarly journals Tomographically reconstructed master equations for any open quantum dynamics

Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 76 ◽  
Author(s):  
Felix A. Pollock ◽  
Kavan Modi
Keyword(s):  
Quantum Dynamics ◽  
Equation Of Motion ◽  
Memory Kernel ◽  
Reconstruction Procedure ◽  
Quantum Process ◽  
Time Dynamics ◽  
Open Quantum ◽  
Quantum Process Tomography ◽  
Process Tomography ◽  
Long Time

Memory effects in open quantum dynamics are often incorporated in the equation of motion through a superoperator known as the memory kernel, which encodes how past states affect future dynamics. However, the usual prescription for determining the memory kernel requires information about the underlying system-environment dynamics. Here, by deriving the transfer tensor method from first principles, we show how a memory kernel master equation, for any quantum process, can be entirely expressed in terms of a family of completely positive dynamical maps. These can be reconstructed through quantum process tomography on the system alone, either experimentally or numerically, and the resulting equation of motion is equivalent to a generalised Nakajima-Zwanzig equation. For experimental settings, we give a full prescription for the reconstruction procedure, rendering the memory kernel operational. When simulation of an open system is the goal, we show how our procedure yields a considerable advantage for numerically calculating dynamics, even when the system is arbitrarily periodically (or transiently) driven or initially correlated with its environment. Namely, we show that the long time dynamics can be efficiently obtained from a set of reconstructed maps over a much shorter time.

scholarly journals Quantum process tomography of a high-dimensional quantum communication channel

Quantum ◽  
2019 ◽  
Vol 3 ◽  
pp. 138 ◽  
Author(s):  
Frédéric Bouchard ◽  
Felix Hufnagel ◽  
Dominik Koutný ◽  
Aazad Abbas ◽  
Alicia Sit ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Quantum Communication ◽  
Communication Channels ◽  
Key Distribution ◽  
Coarse Grained ◽  
High Dimensional ◽  
Quantum Process ◽  
Quantum Process Tomography ◽  
Process Tomography

The characterization of quantum processes, e.g. communication channels, is an essential ingredient for establishing quantum information systems. For quantum key distribution protocols, the amount of overall noise in the channel determines the rate at which secret bits are distributed between authorized partners. In particular, tomographic protocols allow for the full reconstruction, and thus characterization, of the channel. Here, we perform quantum process tomography of high-dimensional quantum communication channels with dimensions ranging from 2 to 5. We can thus explicitly demonstrate the effect of an eavesdropper performing an optimal cloning attack or an intercept-resend attack during a quantum cryptographic protocol. Moreover, our study shows that quantum process tomography enables a more detailed understanding of the channel conditions compared to a coarse-grained measure, such as quantum bit error rates. This full characterization technique allows us to optimize the performance of quantum key distribution under asymmetric experimental conditions, which is particularly useful when considering high-dimensional encoding schemes.

scholarly journals Ancilla-Assisted Quantum Process Tomography

2003 ◽  
Vol 90 (19) ◽  
Author(s):  
J. B. Altepeter ◽  
D. Branning ◽  
E. Jeffrey ◽  
T. C. Wei ◽  
P. G. Kwiat ◽  
...  
Keyword(s):  
Quantum Process ◽  
Quantum Process Tomography ◽  
Process Tomography

scholarly journals Characterizing d-dimensional quantum channels by means of quantum process tomography

2018 ◽  
Vol 43 (18) ◽  
pp. 4398 ◽  
Author(s):  
J. J. M. Varga ◽  
L. Rebón ◽  
Q. Pears Stefano ◽  
C. Iemmi
Keyword(s):  
Quantum Channels ◽  
Quantum Process ◽  
Quantum Process Tomography ◽  
Process Tomography
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