scholarly journals A squeezed quantum microcomb on a chip

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zijiao Yang ◽  
Mandana Jahanbozorgi ◽  
Dongin Jeong ◽  
Shuman Sun ◽  
Olivier Pfister ◽  
...  
Keyword(s):  
Quantum Computing ◽  
Quantum Information ◽  
High Resolution ◽  
Quantum Information Processing ◽  
Frequency Comb ◽  
Continuous Variable ◽  
Quantum States ◽  
High Resolution Spectroscopy ◽  
Quantum Metrology ◽  
Universal Quantum

AbstractThe optical microresonator-based frequency comb (microcomb) provides a versatile platform for nonlinear physics studies and has wide applications ranging from metrology to spectroscopy. The deterministic quantum regime is an unexplored aspect of microcombs, in which unconditional entanglements among hundreds of equidistant frequency modes can serve as critical ingredients to scalable universal quantum computing and quantum networking. Here, we demonstrate a deterministic quantum microcomb in a silica microresonator on a silicon chip. 40 continuous-variable quantum modes, in the form of 20 simultaneously two-mode squeezed comb pairs, are observed within 1 THz optical span at telecommunication wavelengths. A maximum raw squeezing of 1.6 dB is attained. A high-resolution spectroscopy measurement is developed to characterize the frequency equidistance of quantum microcombs. Our demonstration offers the possibility to leverage deterministically generated, frequency multiplexed quantum states and integrated photonics to open up new avenues in fields of spectroscopy, quantum metrology, and scalable, continuous-variable-based quantum information processing.

scholarly journals Remote State Design for Efficient Quantum Metrology with Separable and Non-Teleporting States

2021 ◽  
Vol 3 (1) ◽  
pp. 228-241
Author(s):  
Rahul Raj ◽  
Shreya Banerjee ◽  
Prasanta K. Panigrahi
Keyword(s):  
Parameter Estimation ◽  
Quantum Information ◽  
Fisher Information ◽  
Quantum Information Processing ◽  
Quantum Fisher Information ◽  
Quantum Correlations ◽  
Quantum States ◽  
Quantum Metrology ◽  
High Quantum ◽  
Non Local

Measurements leading to the collapse of states and the non-local quantum correlations are the key to all applications of quantum mechanics as well as in the studies of quantum foundation. The former is crucial for quantum parameter estimation, which is greatly affected by the physical environment and the measurement scheme itself. Its quantification is necessary to find efficient measurement schemes and circumvent the non-desirable environmental effects. This has led to the intense investigation of quantum metrology, extending the Cramér–Rao bound to the quantum domain through quantum Fisher information. Among all quantum states, the separable ones have the least quantumness; being devoid of the fragile non-local correlations, the component states remain unaffected in local operations performed by any of the parties. Therefore, using these states for the remote design of quantum states with high quantum Fisher information can have diverse applications in quantum information processing; accurate parameter estimation being a prominent example, as the quantum information extraction solely depends on it. Here, we demonstrate that these separable states with the least quantumness can be made extremely useful in parameter estimation tasks, and further show even in the case of the shared channel inflicted with the amplitude damping noise and phase flip noise, there is a gain in Quantum Fisher information (QFI). We subsequently pointed out that the symmetric W states, incapable of perfectly teleporting an unknown quantum state, are highly effective for remotely designing quantum states with high quantum Fisher information.

On the classical character of control fields in quantum information processing

2002 ◽  
Vol 2 (1) ◽  
pp. 1-13
Author(s):  
S.J. van Enk ◽  
H.J. Kimble
Keyword(s):  
Quantum Computing ◽  
Information Processing ◽  
Quantum Information ◽  
Laser Beam ◽  
Quantum State ◽  
Quantum Communication ◽  
Quantum Information Processing ◽  
Laser Fields ◽  
Undesirable Property

Control fields in quantum information processing are almost by definition assumed to be classical. In reality, however, when such a field is used to manipulate the quantum state of qubits, the qubits always become slightly entangled with the field. For quantum information processing this is an undesirable property, as it precludes perfect quantum computing and quantum communication. Here we consider the interaction of atomic qubits with laser fields and quantify atom-field entanglement in various cases of interest. We find that the entanglement decreases with the average number of photons \bar{n} in a laser beam as $E\propto\log_2 \bar{n}/\bar{n}$ for $\bar{n}\rightarrow\infty$.

scholarly journals Selecting lines for spectroscopic (re)measurements to improve the accuracy of absolute energies of rovibronic quantum states

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Péter Árendás ◽  
Tibor Furtenbacher ◽  
Attila G. Császár
Keyword(s):  
Graph Theory ◽  
High Resolution ◽  
Experimental Research ◽  
Spectroscopic Data ◽  
Quantum States ◽  
High Resolution Spectroscopy ◽  
Research Groups

AbstractImproving the accuracy of absolute energies associated with rovibronic quantum states of molecules requires accurate high-resolution spectroscopy measurements. Such experiments yield transition wavenumbers from which the energies can be deduced via inversion procedures. To address the problem that not all transitions contribute equally to the goal of improving the accuracy of the energies, the method of Connecting Spectroscopic Components (CSC) is introduced. Using spectroscopic networks and tools of graph theory, CSC helps to find the most useful target transitions and target wavenumber regions for (re)measurement. The sets of transitions suggested by CSC should be investigated by experimental research groups in order to select those target lines which they can actually measure based on the apparatus available to them. The worked-out examples, utilizing extensive experimental spectroscopic data on the molecules H$$_2^{~16}$$ 2 16 O, $$^{32}$$ 32 S$$^{16}$$ 16 O$$_2$$ 2 , H$$_2^{~12}$$ 2 12 C$$^{16}$$ 16 O, and $$^{14}$$ 14 NH$$_{3}$$ 3 , clearly prove the overall usefulness of the CSC method and provide suggestions how CSC can be used for various tasks and under different practical circumstances.

Proposal for dimensionality testing in QPQ

2018 ◽  
Vol 18 (13&14) ◽  
pp. 1125-1142
Author(s):  
Arpita Maitra ◽  
Bibhas Adhikari ◽  
Satyabrata Adhikari
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum System ◽  
Quantum State ◽  
Quantum Information Processing ◽  
Quantum States ◽  
Quantum Private Query ◽  
Unfair Advantage ◽  
Security Proofs

Recently, dimensionality testing of a quantum state has received extensive attention (Ac{\'i}n et al. Phys. Rev. Letts. 2006, Scarani et al. Phys. Rev. Letts. 2006). Security proofs of existing quantum information processing protocols rely on the assumption about the dimension of quantum states in which logical bits are encoded. However, removing such assumption may cause security loophole. In the present paper, we show that this is indeed the case. We choose two players' quantum private query protocol by Yang et al. (Quant. Inf. Process. 2014) as an example and show how one player can gain an unfair advantage by changing the dimension of subsystem of a shared quantum system. To resist such attack we propose dimensionality testing in a different way. Our proposal is based on CHSH like game. As we exploit CHSH like game, it can be used to test if the states are product states for which the protocol becomes completely vulnerable.

Frequency combs and precision spectroscopy of atomic hydrogen

2019 ◽  
pp. 142-215
Author(s):  
Thomas Udem
Keyword(s):  
High Resolution ◽  
Visible Light ◽  
Laser Spectroscopy ◽  
Quantum Electrodynamics ◽  
Atomic Hydrogen ◽  
Frequency Comb ◽  
Atomic Clock ◽  
Laser Frequency ◽  
High Resolution Spectroscopy ◽  
Frequency Combs

A laser frequency comb allows the phase coherent conversion of the very rapid oscillations of visible light of some 100s of THz down to frequencies that can be handled with conventional electronics. This capability has enabled the most precise laser spectroscopy experiments yet, which have allowed the testing of quantum electrodynamics, to determine fundamental constants and to construct an optical atomic clock. The chapter reviews the development of the frequency comb, derives its properties, and discusses its application for high resolution spectroscopy of atomic hydrogen.

A 23.75-GHz frequency comb with two low-finesse filtering cavities in series for high resolution spectroscopy

2015 ◽  
Vol 24 (2) ◽  
pp. 024213 ◽  
Author(s):  
Lei Hou ◽  
Hai-Nian Han ◽  
Wei Wang ◽  
Long Zhang ◽  
Li-Hui Pang ◽  
...  
Keyword(s):  
High Resolution ◽  
Frequency Comb ◽  
High Resolution Spectroscopy ◽  
In Series

scholarly journals Generating superposition of up-to three photons for continuous variable quantum information processing

2013 ◽  
Vol 21 (5) ◽  
pp. 5529 ◽  
Author(s):  
Mitsuyoshi Yukawa ◽  
Kazunori Miyata ◽  
Takahiro Mizuta ◽  
Hidehiro Yonezawa ◽  
Petr Marek ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Continuous Variable
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