Two-Qubit Unitary Quantum Process Tomography by Multiple-Delay Output Measurements for One Unknown Input Pure State Value

2021 ◽  
Author(s):  
Francois Verdeil ◽  
Yannick Deville ◽  
Alain Deville
Keyword(s):  
Pure State ◽  
Unknown Input ◽  
Quantum Process ◽  
Multiple Delay ◽  
Quantum Process Tomography ◽  
Process Tomography

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

scholarly journals Detection of Properties and Capacities of Quantum Channels

2017 ◽  
Vol 24 (04) ◽  
pp. 1740013 ◽  
Author(s):  
Chiara Macchiavello ◽  
Massimiliano F. Sacchi
Keyword(s):  
Entangled State ◽  
Quantum Channels ◽  
Quantum Process ◽  
Channel Output ◽  
Quantum Process Tomography ◽  
Channel Input ◽  
Process Tomography ◽  
Local Measurements ◽  
System States ◽  
Full Quantum

We review in a unified way a recently proposed method to detect properties of unknown quantum channels and lower bounds to quantum capacities, without resorting to full quantum process tomography. The method is based on the preparation of a fixed bipartite entangled state at the channel input or, equivalently, an ensemble of an overcomplete set of single-system states, along with few local measurements at the channel output.

scholarly journals Quantum Process Tomography of a Controlled-Phase Gate for Time-Bin Qubits

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Hsin-Pin Lo ◽  
Takuya Ikuta ◽  
Nobuyuki Matsuda ◽  
Toshimori Honjo ◽  
William J. Munro ◽  
...  
Keyword(s):  
Quantum Process ◽  
Quantum Process Tomography ◽  
Process Tomography ◽  
Phase Gate ◽  
Controlled Phase Gate

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.

Experimental demonstration of optimized quantum process tomography on the IBM quantum experience

2020 ◽  
pp. 2040004
Author(s):  
Akshay Gaikwad ◽  
Krishna Shende ◽  
Kavita Dorai
Keyword(s):  
Quantum Circuit ◽  
Quantum Gates ◽  
Experimental Demonstration ◽  
Superconducting Qubit ◽  
Quantum Process ◽  
Single Qubit ◽  
Quantum Process Tomography ◽  
Process Tomography ◽  
Quantum Processor ◽  
Least Squares Optimization

We experimentally performed complete and optimized quantum process tomography of quantum gates implemented on superconducting qubit-based IBM QX2 quantum processor via two constrained convex optimization (CCO) techniques: least squares optimization and compressed sensing optimization. We studied the performance of these methods by comparing the experimental complexity involved and the experimental fidelities obtained. We experimentally characterized several two-qubit quantum gates: identity gate, a controlled-NOT gate, and a SWAP gate. The general quantum circuit is efficient in the sense that the data needed to perform CCO-based process tomography can be directly acquired by measuring only a single qubit. The quantum circuit can be extended to higher dimensions and is also valid for other experimental platforms.

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