arXiv subjects

Michael Gould

Publications and source records attributed to Michael Gould.

8 recordsLinked to original sources

arXiv2023

UJI Probes: Dataset of Wi-Fi Probe Requests

This paper focuses on the creation of a new, publicly available Wi-Fi probe request dataset. Probe requests belong to the family of management frames used by the 802.11 (Wi-Fi) protocol. As the situation changes year by year, and technology improves probe request studies are necessary to be done on up-to-date data. We provide a month-long probe request capture in an office environment, including work days, weekends, and holidays consisting of over 1 400 000 probe requests. We provide a description of all the important aspects of the dataset. Apart from the raw packet capture we also provide a Radio Map (RM) of the office to ensure the users of the dataset have all the possible information about the environment. To protect privacy, user information in the dataset is anonymized. This anonymization is done in a way that protects the privacy of users while preserving the ability to analyze the dataset to almost the same level as raw data. Furthermore, we showcase several possible use cases for the dataset, like presence detection, temporal Received Signal Strength Indicator (RSSI) stability, and privacy protection evaluation.

cs.NI↗

arXiv2022

What Your Wearable Devices Revealed About You and Possibilities of Non-Cooperative 802.11 Presence Detection During Your Last IPIN Visit

The focus on privacy-related measures regarding wireless networks grew in last couple of years. This is especially important with technologies like Wi-Fi or Bluetooth, which are all around us and our smartphones use them not just for connection to the internet or other devices, but for localization purposes as well. In this paper, we analyze and evaluate probe request frames of 802.11 wireless protocol captured during the 11th international conference on Indoor Positioning and Indoor Navigation (IPIN) 2021. We explore the temporal occupancy of the conference space during four days of the conference as well as non-cooperatively track the presence of devices in the proximity of the session rooms using 802.11 management frames, with and without using MAC address randomization. We carried out this analysis without trying to identify/reveal the identity of the users or in any way reverse the MAC address randomization. As a result of the analysis, we detected that there are still many devices not adopting MAC randomization, because either it is not implemented, or users disabled it. In addition, many devices can be easily tracked despite employing MAC randomization.

cs.CR↗

arXiv2022

Exploration of User Privacy in 802.11 Probe Requests with MAC Address Randomization Using Temporal Pattern Analysis

Wireless networks have become an integral part of our daily lives and lately there is increased concern about privacy and protecting the identity of individual users. In this paper we address the evolution of privacy measures in Wi-Fi probe request frames. We focus on the lack of privacy measures before the implementation of MAC Address Randomization, and on the way anti-tracking measures evolved throughout the last decade. We do not try to reverse MAC address randomization to get the real ad-dress of the device, but instead analyse the possibility of further tracking/localization without needing the real MAC address of the specific users. To gain better analysis results, we introduce temporal pattern matching approach to identification of devices using randomized MAC addresses.

cs.CR↗

arXiv2018

400%/W second harmonic conversion efficiency in $\mathrm{14 μm}$-diameter gallium phosphide-on-oxide resonators

Second harmonic conversion from 1550~nm to 775~nm with an efficiency of 400% W$^{-1}$ is demonstrated in a gallium phosphide (GaP) on oxide integrated photonic platform. The platform consists of doubly-resonant, phase-matched ring resonators with quality factors $Q \sim 10^4$, low mode volumes $V \sim 30 (λ/n)^3$, and high nonlinear mode overlaps. Measurements and simulations indicate that conversion efficiencies can be increased by a factor of 20 by improving the waveguide-cavity coupling to achieve critical coupling in current devices.

physics.app-ph↗

arXiv2018

Frequency control of single quantum emitters in integrated photonic circuits

Generating entangled graph states of qubits requires high entanglement rates, with efficient detection of multiple indistinguishable photons from separate qubits. Integrating defect-based qubits into photonic devices results in an enhanced photon collection efficiency, however, typically at the cost of a reduced defect emission energy homogeneity. Here, we demonstrate that the reduction in defect homogeneity in an integrated device can be partially offset by electric field tuning. Using photonic device-coupled implanted nitrogen vacancy (NV) centers in a GaP-on-diamond platform, we demonstrate large field-dependent tuning ranges and partial stabilization of defect emission energies. These results address some of the challenges of chip-scale entanglement generation.

physics.app-ph↗

arXiv2016

Efficient extraction of zero-phonon-line photons from single nitrogen-vacancy centers in an integrated GaP-on-diamond platform

Scaling beyond two-node quantum networks using nitrogen vacancy (NV) centers in diamond is limited by the low probability of collecting zero phonon line (ZPL) photons from single centers. Here, we demonstrate GaP-on-diamond disk resonators which resonantly couple ZPL photons from single NV centers to single-mode waveguides. In these devices, the probability of a single NV center emitting a ZPL photon into the guided waveguide mode after optical excitation can reach 9%, due to a combination of resonant enhancement of the ZPL emission and efficient coupling between the resonator and waveguide. We verify the single-photon nature of the emission and experimentally demonstrate both high in-waveguide photon numbers and substantial Purcell enhancement for a set of devices. These devices may enable scalable integrated quantum networks based on NV centers.

cond-mat.mes-hall↗

arXiv2015

A Large-Scale GaP-on-Diamond Integrated Photonics Platform for NV Center-Based Quantum Information

We present chip-scale transmission measurements for three key components of a GaP-on-diamond integrated photonics platform: waveguide-coupled disk resonators, directional couplers, and grating couplers. We also present proof-of-principle measurements demonstrating nitrogen-vacancy (NV) center emission coupled into selected devices. The demonstrated device performance, uniformity and yield place the platform in a strong position to realize measurement-based quantum information protocols utilizing the NV center in diamond.

cond-mat.mes-hall↗

arXiv2014

Room-temperature detection of single 20 nm super-paramagnetic nanoparticles with an imaging magnetometer

We demonstrate room temperature detection of single 20 nm super-paramagnetic nanoparticles (SPNs) with a wide-field optical microscope platform suitable for biological integration. The particles are made of magnetite (Fe3O4) and are thus non-toxic and biocompatible. Detection is accomplished via optically detected magnetic resonance imaging using nitrogen-vacancy defect centers in diamond, resulting in a DC magnetic field detection limit of 2.3 μT. This marks a large step forward in the detection of SPNs, and we expect that it will allow for the development of magnetic-field-based biosensors capable of detecting a single molecular binding event.

cond-mat.mes-hall↗