Browsing by Author "Khalifa, Hany"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Microwave Gaussian quantum sensing with a CNOT gate receiver
    (IEEE, 2023-09-22) Khalifa, Hany; Petrovnin, Kirill; Jantti, Riku; Paraoanu, Gheorghe Sorin; Department of Information and Communications Engineering; Superconducting Qubits and Circuit QED; Centre of Excellence in Quantum Technology, QTF; Department of Information and Communications Engineering; Department of Applied Physics
    In quantum illumination (QI) the non-classical correlations between continuous variable (CV) entangled modes of radiation are exploited to detect the presence of a target embedded in thermal noise. The extreme environment where QI outperforms its optimal classical counterpart suggests that applications in the microwave domain would benefit the most from this new sensing paradigm. However all the proposed QI receivers rely on ideal photon counters or detectors, which are not currently feasible in the microwave domain. Here we propose a new QI receiver that utilises a CV controlled not gate (CNOT) in order to perform a joint measurement on a target return and its retained twin. Unlike other QI receivers, the entire detection process is carried out by homodyne measurements and square-law detectors. The receiver exploits two squeezed ancillary modes as a part of the gate’s operation. These extra resources are prepared offline and their overall gain is controlled passively by a single beamsplitter parameter. We compare our model to other QI receivers and highlight the conditions in which it outperforms others and achieves optimal performance. Although the main focus of this study is microwave quantum sensing applications, our proposed device can be built as well in the optical domain, thus rendering it as a new addition to the quantum sensing toolbox in a wider sense.
  • Thumbnail Image
    Item
    Microwave quantum communications: new approaches to sensing and mitigation of the bosonic pure-loss channel
    (Aalto University, 2024) Khalifa, Hany; Paraoanu, Sorin, Dr., Aalto University, Department of Applied Physics, Finland; Informaatio- ja tietoliikennetekniikan laitos; Department of Information and Communications Engineering; Sähkötekniikan korkeakoulu; School of Electrical Engineering; Jäntti, Riku, Prof., Aalto University, Department of Information and Communications Engineering, Finland
    With the current availability of microwave quantum technologies, it is imperative to investigate the different methods and techniques that would enhance the performance of currently existing microwave communication systems. There are two particular areas of interest that are considered in this thesis: (1) quantum microwave sensing in the presence of extreme additive white Gaussian noise, and (2) the imperfect propagation and storage of bosonic modes inside lossy transmission media. Due to the small signal powers in the microwave domain, the task of finding the most efficient detection method for the completion of the aforementioned tasks while maintaining the quantum advantage is complicated. In this thesis, novel methods and techniques are proposed that ease the experimental requirements for microwave quantum technologies. The thesis comprizes four main publications that summarize the research investigation. Publications I and II consider the problem of physically realizing microwave quantum illumination without the need for ideal single-photon counters. Firstly, publication I studies the effect of the excess noise and losses induced by the environment on the utilized signal-idler pair. Then, publication II provides a novel solution, a CNOT (controlled not) gate quantum illumination receiver that achieves an optimal performance set for a quantum illumination receiver without the need for single-photon counters. In publications III and IV, the focus is on devising new strategies to mitigate the losses experienced by microwave bosonic modes during propagation or storage. The objective here is to adapt the concept of noiseless linear amplification, earlier demonstrated in the optical domain, to the microwave region. Despite the persistent problem of microwave detection, the novel one-way noiseless linear amplifier based on quantum non-demolition detectors managed to outperform a conventional one based on microwave photon counters. Furthermore, it also offered an uninterrupted performance due to its fault tolerance which could not be replicated by a conventional noiseless linear amplifier. Finally, publication IV considers several future applications of one-way noiseless linear amplifiers in sensing, remote entanglement sharing and secret key generation, where the device demonstrated in this thesis is able to outperform any other conventional noiseless linear amplifier.
  • Thumbnail Image
    Item
    Quantum backscatter communication with photon number states
    (2018) Khalifa, Hany; Jäntti, Riku; Department of Communications and Networking; Communication Engineering; Department of Communications and Networking
    Backscattered signals are always obscured by the unavoidable channel noise. However, by exploiting quantum physics recent protocols had been developed to enhance the probability of detecting backscattered signals in a very noisy environment [1], [2]. In this paper we propose a new detection scheme that is simpler in nature than the sum frequency receiver that was proposed for the quantum illumination protocol [3]. Signals are generated using spontaneous parametric down conversion (SPDC) and are transmitted via the simple modulation technique of on-off keying (OOK), while the receiver design will rely upon the purely non-classical Hong-Ou-Mandel (HOM) effect.
  • Thumbnail Image
    Item
    Quantum Backscatter Communication: A New Paradigm
    (2018) Di Candia, Roberto; Jäntti, Riku; Duan, Ruifeng; Lietzén, Jari; Khalifa, Hany; Ruttik, Kalle; Department of Communications and Networking; Communication Engineering; Wireless & Mobile Communications; Department of Communications and Networking; Freie Universität Berlin
    In this paper, we propose a novel quantum backscatter communications (QBC) protocol, inspired by the quantum illumination (QI) concept. In the QBC paradigm, the transmitter generates entangled photon pairs. The signal photon is transmitted and the idler photon is kept at the receiver. The tag antenna communicates by performing the pulse amplitude modulation (PAM), binary phase shift keying (BPSK) or quadratic phase shift keying (QPSK) on the signal impinging at the antenna. Using the sum-frequency-generation receiver, our QBC protocol achieves a 6 dB error exponent gain for PAM and BPSK, and 3 dB gain for QPSK over its classical counterpart. Finally, we discuss the QI-enhanced secure backscatter communication.
  • Thumbnail Image
    Item
    Quantum-Enhanced Microwave Backscattering Communications
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2020-01-01) Jantti, Riku; Duan, Ruifeng; Lietzen, Jari; Khalifa, Hany; Hanzo, Lajos; Department of Communications and Networking; Communication Engineering; Communications Theory; Department of Communications and Networking; University of Southampton
    The recent advances in the field of microwave superconducting circuits open the way for a multitude of engineering applications that revolutionize the field of classical communications. To exploit this new technology, we propose a novel microwave quantum-enhanced backscattering system based on the laws of quantum physics. Both the transmitter and the receiver are quantum mechanical in nature and are accommodated at the infrastructure side, while the backscattering device is classical. The advocated system breaks the performance barrier of the classical backscattering systems and approaches the ultimate attainable receiver sensitivity. Finally, our quantum solution outperforms the classical solutions in terms of its level of security.
  • Thumbnail Image
    Item
    Retrieving quantum backscattered signals in the presence of noise
    (2019-12-01) Khalifa, Hany; Jäntti, Riku; Department of Communications and Networking; Communication Engineering; Communication Engineering
    Quantum sensing based on entangled photon pairs is gradually establishing itself as a cornerstone in modern communication networks. The unrivalled capability of quantum sensing techniques in distilling signals plagued by noise, renders them suitable for deployment in backscatter communication networks. Several attempts have been made recently to utilize pairs of entangled signal- idler photons, to enhance the sensitivity of photo- detection in backscatter networks. However, these efforts have always assumed the lossless retention of the idler mode, which is a challenging task from a practical perspective. In this study we examine the extent to which quantum correlations remain after retaining the idler mode in a lossy memory element, while the signal photon propagates through a lossy thermal channel as usual. We also examine briefly two different detection methods, and estimate the received signal-to-noise ratio for them both. This new proposed model is one step further towards realizing quantum backscatter communication.