BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Compensating decoherence of squeezed light in cavity-enhanced quan
 tum metrology
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4783@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Quantum states of light are being more commonly used to increa
 se the sensitivity of various sensors. They allow to reach high sensitivit
 y without using significant light power\, and thus find application in var
 ious fields\, from biological sensing to gravitational-wave detection. At 
 the same time\, these states are very fragile\, and even a small amount of
  decoherence can significantly reduce their benefit. We propose a new appr
 oach that allows to compensate part of quantum decoherence\, thus increasi
 ng the sensitivity beyond the previously established decoherence-induced q
 uantum limit. To achieve this\, we use an optimally tuned quantum squeezer
  placed directly inside the detector cavity. This squeezer operates to res
 tore the externally injected squeezing or to amplify the signal\, dependin
 g on the level of loss. It can be flexibly tuned to the optimal operation.
  We present the first experimental combination of intra-cavity and externa
 lly injected squeezing used to enhance detector’s sensitivity. We demons
 trate for the first time how optimal tuning allows to compensate quantum d
 ecoherence. Finally\, we derive the new decoherence-induced quantum limit.
  Based on this approach\, we develop the quantum expander for the detectio
 n bandwidth of GW detectors\, which allows to significantly increase the s
 ensitivity at high frequencies.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event
 /255/contributions/4783/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4783/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juggled interferometer for gravitational wave detection
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4784@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Juggled interferometer (JIFO) is a novel type of earthbound gr
 avitational wave detector targeting a frequency band of 0.1–10 Hz. By us
 ing repeatedly free-falling test masses\, JIFO can in principle decouple t
 est masses from the seismically noisy environment and avoid suspension the
 rmal noise in a straightforward manner. Since the test masses are in a wei
 ghtless state\, as is the case with space gravitational wave detectors\, J
 IFO would be a good testbed for technologies of space projects. \n\nHere\,
  the concept of the Michelson-type JIFO is introduced. Then the experiment
  setup and the data readout method of a JIFO are discussed. Considering th
 e displacement noise budget of the Einstein Telescope (ET)\, we show that 
 the juggled test masses could significantly improve the sensitivity at 0.1
 -2.5 Hz even with discontinuous data. The science cases brought with the i
 mproved sensitivity would include detecting quasi-normal modes of black ho
 les with 104-105 Msun\, testing Brans-Dicke theory with black-hole and neu
 tron-star inspirals\, and detecting primordial-black-hole-related gravitat
 ional waves.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contributions/
 4784/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4784/
END:VEVENT
BEGIN:VEVENT
SUMMARY:SpicyPy: a common python tool for signal processing and control sy
 stems
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4785@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Within gravitational wave research community (including but no
 t limited to LIGO-Virgo-KAGRA\, Einstein Telescope and LISA collaborations
 ) a lot of work in understanding and improving the detectors involves sign
 al processing and modelling of control systems. Historically\, different s
 oftware tools were used for these purposes. We believe that it is possible
  to create a single software tool that can be useful for many different ap
 plications in these domains. This would help to facilitate exchange of kno
 wledge between collaborations\, and could be used in teaching.\n\nWe aim t
 o develop a python package intended as a general tool with a simple but po
 werful interface to facilitate control systems modelling\, signal processi
 ng\, and provide an interface between the two. It may rely on other well-k
 nown and tested packages already used for these applications\, but it will
  abstract interactions with them with a unified interface. Potential appli
 cations include time series analysis\, suspensions modelling\, feeding sen
 sor signals through a control system\, and more. The project is a collabor
 ative open-source effort across the groups from the start\, and new contri
 butors are always welcome. We are currently focused on compiling software 
 requirements specification and are in discussions with researches from dif
 ferent collaborations to understand the most common potential applications
 .\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4785/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4785/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Substrate transferred aluminum gallium arsenide (AlGaAs) crystalli
 ne coatings
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4788@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Substrate-transferred crystalline coatings made from aluminum 
 gallium arsenide (AlGaAs) have very low thermal noise compared to the ion 
 beam deposited amorphous oxides used until now in gravitational wave detec
 tors.  AlGaAs coatings also show excellent optical properties and both the
 rmal noise and optical performance has been demonstrated in other precisio
 n optics applications.  The primary challenge to using AlGaAs coatings in 
 future detectors is the coating diameter necessary and the large mass and 
 thickness of the test mases.  We present results on 10 cm diameter AlGaAs 
 coatings and propose multiple pathways to implement AlGaAs coatings on upg
 rades to current detectors with up to 40 kg masses and on future detectors
  with larger masses. We also show schedule and budget plans that allow AlG
 aAs to be used in future gravitational wave detectors.\n\nhttps://indico.i
 crr.u-tokyo.ac.jp/event/255/contributions/4788/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4788/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optical absorption of TiO$_{2}$ doped SiO$_{2}$ as a replacement h
 igh index coating material
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4808@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:The sensitivity of 3rd generation gravitational wave detectors
  is currently projected to be\nlimited by the level of Brownian coating th
 ermal noise produced from highly reflecting\nmirror coatings.  In the curr
 ent detectors layers of Ta$_2$O$_5$\, a material with higher\nrefractive i
 ndex (n = 2.14)\, has higher levels of optical absorption compared the low
 er index\nlayers of SiO$_ {2}$ (n=1.44). To improve detector sensitivity a
 nd duty cycle\, the optical and\nmechanical properties of new doped coatin
 g materials are being investigated. This work\npresents measurements of th
 e optical absorption of SiO$_2$ and SiO$_2$ doped with\nTiO$_2$ layers as 
 part of a highly reflecting coating stack. Utilising the photothermal\ncom
 mon-path interferometry technique\, we discuss the effects of heat treatme
 nt and\ncrystallisation on the optical performance of the material compare
 d to current aLIGO \ncoatings.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/
 255/contributions/4808/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4808/
END:VEVENT
BEGIN:VEVENT
SUMMARY:TiO$_{2}$:SiO$_{2}$ coating thermal noise and optical studies
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4809@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Current gravitational wave detectors are limited in their most
  sensitive frequency range by the mirror coating thermal noise which arise
 s from the Brownian motion of the coating materials on the interferometer 
 test mass optics. For the next generation detector upgrades and beyond\, i
 t is imperative to find coating materials/topologies that reduce this mech
 anical effect\, whilst still meeting the desired optical requirements.  Ti
 tania-doped silica had been identified as a coating material candidate whi
 ch could potentially improve detector sensitivity. \n\nWe present here our
  investigations into the mechanical and optical properties of highly-refle
 ctive coating stacks made of pure SiO2 and TiO2 doped SiO2\, deposited via
  ion beam sputtering (IBS). Two different concentrations of TiO2 doping in
  the high-refractive index layers of our coating stacks were investigated\
 , with mechanical loss and optical absorption being measured through diffe
 rent steps of heat treatment for each\, with the level of coating thermal 
 noise being calculated from the former.\n\nhttps://indico.icrr.u-tokyo.ac.
 jp/event/255/contributions/4809/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4809/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Angular Signal Amplification with a Coupled Cavity for Torsion-Bar
  Antenna
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4851@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Torsion-Bar Antenna (TOBA) is a ground-based gravitational wav
 e detector using a torsion pendulum. The resonant frequency of torsional m
 otion is ~1 mHz\, therefore TOBA has good design sensitivity of $10^{-19} 
 \\\, / \\sqrt{\\mathrm{Hz}}$ at 0.1 Hz in low frequencies (0.1 Hz – 10 H
 z). TOBA can detect intermediate mass black hole binary mergers\, Newtonia
 n noise\, and so on. A prototype detector Phase-III TOBA with a 35 cm-scal
 e pendulum is under development to demonstrate noise reduction. The target
  sensitivity is set to $10^{-15} \\\, / \\sqrt{\\mathrm{Hz}}$ at 0.1 Hz. T
 o achieve our target sensitivity\, we need to measure the pendulum rotatio
 n precisely. We propose a coupled wavefront sensor (Coupled WFS) as an ang
 ular sensor for Phase-III TOBA. In our method\, an auxiliary cavity is use
 d to compensate Gouy phase of a main cavity and enhance the first-order TE
 M modes in the main cavity. The experimental demonstration was successfull
 y performed in 2021. In this workshop\, we will show the principle and dem
 onstration results of a Coupled WFS.\n\nhttps://indico.icrr.u-tokyo.ac.jp/
 event/255/contributions/4851/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4851/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Estimating the Newtonian noise of groundwater at the KAGRA
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4854@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Changes due to gravitational waves are very small\, so noise i
 s generated due to various factors. KAGRA was built 300 meters underground
  to reduce ground vibrations. The groundwater generated underground is dis
 charged through pipes. The gravity gradient generated by the universal gra
 vitation force due to the oscillation of the water surface through the pip
 e may cause the mirror of KAGRA to shake and become a noise to the target 
 sensitivity of KAGRA. \nOur experiment was conducted using the simulation 
 software Flow-3D in order to know the magnitude of Newtonian noise. The Ne
 wtonian noise was evaluated by calculating the waveform of the flowing wat
 er.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4854/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4854/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Control of Dual-Pass Fabry-Perot Cavity for space gravitational wa
 ve antennas : DECIGO and B-DECIGO
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4855@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:A dual-pass Fabry-Perot cavity will be used for DECIGO (DECi-h
 ertz Interferometer Gravitational-wave observatory) and B-DECIGO. To detec
 t gravitational waves\, it is necessary to establish the method to control
  the dual-pass Fabry-Perot cavity. We can divide this issue in two parts\,
  “Length control” and “Alignment control”. For Length control\, it
  is demonstrated that we can control the length of dual-pass Fabry Perot c
 avity with Pound-Drever-Hall technique. On the other hand\, for Alignment 
 control\, though the method was already proposed (WaveFront Sensor and Bea
 m Pointing Control)\, it is not demonstrated yet. Therefore\, an experimen
 t is needed for the demonstration.In this poster\, we show the principle t
 o control the dual-pass Fabry-Perot cavity in the direction of the angle a
 nd explain the experiment to demonstrate it.\n\nhttps://indico.icrr.u-toky
 o.ac.jp/event/255/contributions/4855/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4855/
END:VEVENT
BEGIN:VEVENT
SUMMARY:CO2 mode cleaner for Thermal Compensation System of Advanced Virgo
 +
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4846@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:As planned for its fifth observation run O5\, Advanced Virgo+ 
 will have 80 Watts in main laser. The absorption of laser power in the int
 erferometer's core optics leads to thermal effects causing optical aberrat
 ions\, ultimately preventing interferometer's operation. To recover detect
 or's ideal operation\, Thermal Compensation System (TCS) is needed to corr
 ect wavefront distortions. In particular\, to correct the axisymmetric par
 t of the spurious thermal lens in the power recycling cavity\, a heating p
 attern is projected on a compensation plate using Double Axicon System (DA
 S) where a 50 Watts CO2 laser beam is reshaped using axicons.  Due to O5 s
 tringent requirements on the residual of DAS correction\, heating pattern 
 distortions caused by the known amount of higher-order modes (HOM) in the 
 CO2 beam cannot be tolerated. To remove these HOMs\, we are constructing a
 n optical mode cleaner which will allow us to retain 95% of the CO2 laser 
 power for compensation with a strong reduction of HOM related residual cor
 rection. To our knowledge\, this is the first time a mode cleaner is desig
 ned for a high power CO2 laser. We present here the requirements\, motivat
 ion and current status of the work\, discussing the issues related to the 
 CO2 wavelength and power.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/255/c
 ontributions/4846/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4846/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vibration analysis of ETpathfinder cryogenic heat-links
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4819@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:The Einstein Telescope pathfinder (ETpathfinder) is a cryogeni
 c testbed for the next generation of gravitational-waves antennas. To reac
 h the target temperature of 18 K\, ETpathfinder cryogenic payloads are des
 igned to extract heat from the test masses by integrating low stiffness an
 d highly conductive heat-links that connect to the cryocoolers. Since the 
 interferometer test masses are very sensitive to mechanical vibrations\, t
 he noise from the cryocoolers through the heat conductor should be careful
 ly monitored and controlled. This work presents the modeling and experimen
 tal measurements of the mechanical vibrations transferred by the heat-link
 s in a dedicated payload setup. To investigate the stability criterion of 
 the cold-head\, seismic noise propagated via the heat-links is then projec
 ted to the displacement sensitivity of ETpathfinder.\n\nhttps://indico.icr
 r.u-tokyo.ac.jp/event/255/contributions/4819/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4819/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Measuring thermal noise in gram-scale Si flexures at 123 K
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4817@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Future terrestrial gravitational wave detectors are limited by
  fundamental noise sources\, one of which is the thermal noise arising in 
 the test masses and suspensions in the frequency band where ground-based d
 etectors are sensitive. To mitigate this noise\, future detectors are envi
 sioned to operate at cryogenic temperatures using silicon optics as test m
 asses and silicon ribbons to suspend the test masses. Silicon ribbons rese
 mble cantilever topology\, and therefore studying the thermal noise in the
  flexing of a gram-scale silicon cantilever is analogous to the suspension
  thermal noise encountered in these ribbon suspensions. At the Australian 
 National University\, I have built an operational cryogenic infrastructure
  to measure the broadband thermal noise of silicon flexures at 123 K. In t
 his talk\, I will present initial results of our cool-down tests\, thermal
  noise measurements from the experiment and future plans.\n\nhttps://indic
 o.icrr.u-tokyo.ac.jp/event/255/contributions/4817/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4817/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vibration Analysis of KAGRA Cryostat at Cryogenic Temperature
DTSTART;VALUE=DATE-TIME:20220527T043000Z
DTEND;VALUE=DATE-TIME:20220527T063000Z
DTSTAMP;VALUE=DATE-TIME:20260715T045318Z
UID:indico-contribution-1190-4810@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Large-scale Cryogenic Gravitational-Wave Telescope\, KAGRA is 
 a second-generation gravitational-wave detector (GWD) located in Japan. Th
 e features that distinguish KAGRA from other GWDs are its underground loca
 tion and cryogenic operation of the four main mirrors. The underground loc
 ation provides a quiet site with low seismic noise\, while the cryogenic o
 peration cools the mirrors down to 20 K\, reducing the thermal noises. How
 ever\, cryocooler vibration and structural resonances of the cryostat can 
 contaminate detector sensitivity as they couple to test mass through the h
 eat-links. Monitoring and characterization of the vibration inside the cry
 ostat is critical for the optimum noise performance of KAGRA. \nIn April\,
  2020 KAGRA conducted an international observation run\, "O3GK" along with
  GEO600. During this run several noise sources were identified and a noise
  budget was prepared.  However\, as the mirrors were not cooled the noise 
 transfer via heat-links was estimated based on room temperature\, in vacuu
 m vibration measurement performed 2.5 years before O3GK. During the upcomi
 ng observation run the mirrors will be cooled down\, so we performed vibra
 tion analysis of the cooling system at cryogenic temperature to study its 
 impact on detector sensitivity. In this poster\, we describe the KAGRA coo
 ling system and discuss the results of vibration analysis.\n\nhttps://indi
 co.icrr.u-tokyo.ac.jp/event/255/contributions/4810/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4810/
END:VEVENT
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