I am now on the verge to start my fourth and final year as a PhD student at the University of Birmingham, with my GraWIToN contract ending within a month. However, I have received six months of extended funding through my University, and I am aiming on submitting my thesis by the end of this period, which means by the end of March 2018. Currently, the thesis is still in a planning phase (i.e. I have not yet started to write it), but this will go into a more active writing phase by the start of October 2017. I have recently published my first first-author paper with the title "Multi-spatial-mode effects in squeezed-light-enhanced gravitational wave detectors", where we show how squeezed light is affected by spatial mode mismatches, and that squeezing higher-order modes potentially can mitigate the negative effects of spatial mode mismatches. This paper, together with alignment sensing and contrl modelling for advanced LIGO, and longitudinal sensing and contrl modelling for advanced Virgo, will constitute integral parts of my thesis.

We have had two GraWIToN network schools since the last newsletter. The first one was in Hannover and focused on lasers, optics, and optical simulations. I found it interesting and useful both for learning and discussing work topics and for networking with the other attendees. Especially, I enjoyed the lectures on non-classical light. The second network school was at Virgo site outside Pisa and taught us communication and management of large projects, and it ended with us GraWIToNs spending a half day conceptually designing an outreach exhibition together with school kids. The science communication part was interesting and certainly important to work on, and the last outreach event was fun and a good experience. However, I cannot say that I was very susceptible to learn how to manage large projects – even though I do find it interesting in general, and it may potentially be of importance in my future career – but it did not feel very relevant at the moment, and at the time I was too stressed out with my own work to be fully focused.

I spent two months in the end of last year (2016) at the Virgo site, close to Pisa in Italy. I mainly worked on modelling how mirror misalignments affect the longitudinal contrl of the near-unstable power recycling cavity of the gravitational wave detector Advanced Virgo. This proved to be more challenging than expected, as so often with optical modelling. The challenge was to understand how to accurately model the combination of a near-unstable cavity and misaligned mirrors, which creates relatively large perturbations to the ideally Gaussian-shaped laser beam. However, we ultimately learned how to successfully perform the simulations. I had two interesting and fun months of long working days in the Virgo contrl room, where I was sitting among the commissioning team that intensively were working towards joining Advanced LIGO in its search for more gravitation wave sources. I also enjoyed the experience of living and working in Italy, being surrounded by the Italian food, culture and language.

I have had the pleasure of being a GraWIToN for nearly three years now. The Marie Curie actions programme has meant many things to me. When agreeing to come to the University of Birmingham to work as an early stage researcher (ESR), the Marie Curie Actions programme meant that I did not have to give up a taxable income with social security benefits for the opportunity to go to UK to do my PhD, which definitely made my choice to accept the offer much easier. During my time as a GraWIToN ESR, the programme has given me a great group of people around Europe that I have felt connected to, and always been looking forward to meet at network schools and conferences. The programme took me to Germany and Italy for totally 3 months to collaborate with other physicists. The generous travel budget has allowed me to travel to many conferences and meetings around the world to give talks and present posters, which has increased my visibility in the field and provided great network opportunities. All of these are experiences that I value very highly, both professionally for my future career, and personally on a private level.

It's been a year since the last newsletter and many things happened, but the most exciting were the last ones. During all this time, many of us have been working close to Virgo and we were looking forward to see the day it would start taking data together with our LIGO colleagues. So this happened the 1st of August when Virgo started its science. But arriving to that point had not all been plain sailing. During commissioning many challenges were faced and happily it was possible to increment the range for BNS from less than 10Mpc to 25Mpc in less than 2 months.

In parallel to the commissioning during the first week of July I had the opportunity to go to the Amaldi conference. The conference was held in Pasadena, California and it was a meeting point for the gravitational wave community. Also it was a great working week because for first time I could give a talk and present a poster. That was a great experience.

But before this exciting period lots of things happened!

From the grawiton project, I attended to two (and a half) schools. The first one was held on Hanover during September 2016, this one was the 2nd Tech school on optics. Then it came the short school Data analysis and machine learning that was held at Virgo taking advantage to the fact that there was a visitor from the collaboration working with those techniques. The last grawiton school was devoted to project management of big scientific projects. The last grawiton school was special because it was the last time that all grawiton students could met together during our thesis, I hope we can meet all again soon!

On my outreach activities I collaborated with the organisation of the Internet Festival in Pisa explaining Virgo and gravitational waves to the general public. This was a beautiful experience because explaining what are gravitational waves to children not only is difficult, but it means that at least you understand them.

But the last year was not only spend doing activities outside my office. It's been hard, but finally I could develop a ray tracing software that can be used to find out the noise generated by mechanical elements moving at a certain frequency. I am sure that there are still bugs to be found, but I am quite sure that the method is working. And I hope that soon some results of the noise produced by an external detection bench will be seen soon.

In this newsletter I would like to share my research work experience at Virgo detector located in Cascina near to Pisa, Italy. I joined the Squeezing group at Virgo for my thesis work, which is responsible for the development of a squeezed light source to reduce the quantum noise effect in interferometric measurements for Gravitational waves (GW) interferometers. I am about to finish the second year of my PhD course, and by the end of December 2018, I will finish the PhD program. Just to give an idea, what quantum noise is and how does it affect the interferometric measurement.

Quantum Noise (QN) arises due to the quantum nature of light itself, and it comprises of photon shot noise at high frequencies (photon counting error) and the photon radiation pressure noise at low frequencies, when light field is measured with a photodiode. The photons in a laser source follow Poisson statistics instead of being equally distributed. The photon shot noise can be sensed in measurement, where one can see fluctuations in the voltage signal monitored on a oscilloscope for instance, while the photon radiation pressure noise makes the test masses to displace around their equilibrium position. Since the very basic principle of GW measurement involves the test masses to be quieter than the signal you want to measure and also, no noise due to measurement itself to affect the detection, so QN needs to be addressed to improve the GW interferometer’s detection performance. These principles put tight limit on the noise sources to be eliminated out of the interferometer in order to detect the tiny ripples in the fabric of spacetime caused by the GW. Shot noise dominates above 100 Hz up to 10 KHz in the GW detection bandwidth and attenuating the shot noise increases the radiation pressure noise, which is present below 100 Hz. The future upgrades of GW detectors need the reduction of QN to improve the sensitivity in most of their detection band and thus to enhance the reach of detectors further deep into the universe.

In order to address the challenge of QN, Injecting squeezed vacuum states into the interferometer’s output port in a so-called squeezing experiment is a promising solution. The vacuum states allow the reduction in photon shot noise on the expense of increasing the photon radiation pressure noise or vice versa. The idea is to use a nonlinear optical phenomenon to generate squeezed vacuum states for example in degenerate parametric oscillation/amplification process (a 2nd order non linear optical effect). I worked on the development of couple of subsystems for the Virgo squeezing experiment, their installation and alignment on the optical bench. I spent most of my time at the squeezing experiment facility at Virgo site, where we are now implementing the coherent cntrol for the squeezer.

The development of squeezed light source at Virgo site gave me an amazing and challenging experience of work in a clean room. The Virgo site is quite silent and located in beautiful vicinity of Cascina town. This experience allowed me to further improve my experimental skills in optics and to work in collaboration with colleagues from other research groups. I had the opportunity to interact with researchers of other subsystems of the Virgo detector on site to understand this complex instrument and to widen my professional network. I attended the weekly meetings within the collaboration, also the Virgo weeks, which allow the researchers of different subsystems to discuss their research work with the collaboration researchers. Also, I am participating to the GEO600-Virgo collaboration for the development and installation of a new squeezer in Advanced Virgo (AdV) for the next scientific run, which is an exciting collaboration opportunity for Virgo and GEO600. It is an immense pleasure for me to be a member of Virgo collaboration and LIGO-Virgo scientific collaboration.

Apart from the squeezing activity at Virgo site, I spent three months as secondment at Max Planck Institute for Gravitational Physics, which was also a wonderful experience. I worked out an experimental activity on the generation of green light source for squeezing experiment in single pass configuration, which was an effort to optimize the second harmonic generation subsystem for the squeezing experiment. The institute is located in Hannover, Germany and I had the opportunity to explore Germany a bit, though didn’t travel too much. I experienced a different laboratory with helping colleagues and collaborative work environment. Living in Hannover was also a good experience, not a big city, more calm and less crowdy but the weather sometimes can make you a bit uncomfortable with its fluctuating nature.

At present, I am working in the optics group at European Gravitational Observatory (EGO) for the development of all fibered green laser sources for AdV auxiliary lasers. This activity involves the generation of green laser light source in second harmonic generation (SHG) process using single pass configuration. The main advantage of all fibered system is, it eliminates the need of employing additional auxiliary laser sources, the related phase locked loops (PLLs) implementations and ease of optical alignment. It only needs couple of millliwatts of infrared (IR) laser power from the Virgo Master laser, and through an optical amplifier, one can achieve the required amount of IR laser power to produce the desired green laser power, so a simple and economical solution.

I attended the GraWIToN school on laser, optics and simulation held between 12-16 September 2016 at Max Planck Institute for Gravitational Physics, Hannover, Germany and the GraWIToN school on Project Management (PM) held between 21-25 November 2016 at EGO, Cascina, Italy. The LIGO-Virgo collaboration (LVC) meeting in August 2017 at CERN was also an amazing experience. I got the opportunity to visit CERN located at Fraco-Swiss border, the place where some of the most sophisticated and complex instruments are used to understand the interaction of fundamental particles and also to search for new particles, which allows scientists to understand the laws of nature and the structure of the universe.

The GraWIToN project gave me a unique opportunity towards my personal and professional development by allowing me to experience thesis work at one of the leading GW detector in the world, visiting and collaborating with colleagues around the globe and the opportunity to know about diverse culture, traditions and social lives. I would like to thank Marie Skłodowska-Curie actions (MSCA) for providing excellent platform to young researchers to work at the frontiers of science and to contribute to the ongoing human developments in science and technology.

Time flies, and as much as I wish it would slow down a bit a whole year has passed again. Incidentally, it is the first time I’ve written here since I crossed the middle point of my entitled contract. Although this date should not be more than symbolic it has always that slight psychological impact as it marks the moment when one shouldn’t look that much at the starting point anymore but more at the ending one. That’s what I’ve been focusing on in the past year: thinking and acting in a more pragmatic and results-oriented way in order to complete my PhD without requiring a contract extension. And I do think it’s on track!

The first step was to complete the academic training requirements from the University of Glasgow. It was nothing drastic but I was late due to perpetual postponing. Fortunately I was able to mostly rely on the GraWIToN training program organised within the network through several schools. Therefore, after Pisa and Birmingham, I flew to Hanover in last September to join my fellow ESRs during a week of courses on high power lasers. As usual when we gather it was very enjoyable but all the more since the topics of the courses were very close to my field compared to previous schools. It was also my first opportunity to go to Germany after 11 years of learning German so I was quite excited to see how good I could do. Well I hit the ground and went back to English quite quickly…

The next journey was back to Pisa in November and at least there were no expectations there it was going to be English all the way. We gathered all together one last time (or so we thought…) for a project management school which took us a bit away from our usual not-cooperative codes or puzzling  equations and was quite refreshing. We also got the opportunity to work with enthusiastic high school students during a workshop on science communication.

And training-wise that was mostly it; I still had a few more courses to take as it is not allowed to get all the credits from outside the University. It wasn’t that much of an issue as the University also provides a wide range of high quality courses and actually picking only a few was the hardest part. I finally settled on ultrafast photonics, software carpentry and problem solving skills as there were both convenient for me to attend and relevant in my project.

The second step, less trivial was to define where I wanted to end up at the end of my PhD and what I wanted to achieve. It’s been actually quite hard as I have a long lead time for any of my experiments (up to 8 months) so I knew that anything I would decide after May had little chance to be achievable in time. I think I did a good job anticipating (for once!) and around December we sat together with my supervisors and settled on realistic objectives for the thesis. If we did it again now they would probably be somehow reviewed but given the finite nature of the project it is not possible to redefine them every few months and it was important that this was done.

And the last step has been of course to try and work towards these objectives. With a few more secondments at the University of Glasgow among which a 2-month period which was a wonderful experience where work and entertainment perfectly merged, and the background work at Gooch and Housego I managed to advance to being close of completing all my experimental work. Or at least the one that had been planned back in December. I won’t go in the scientific details but in short, I abused my bonds testing a whole lot of their optical and mechanical properties to investigate their suitability for specific products or to get more knowledge on the mechanisms. I also led some cleaning trials to answer issues the company was meeting with their process and some computing work to look at the sensitive issue of thermal stresses in bonded components. There is still some work to do but the largest part has been completed.

So what will I do during my last 6 months? Well first I’m given a few more opportunities to present my work as I’m attending the Einstein Telescope meeting in Glasgow at the beginning of September with all of the ESRs as a wrap up farewell gathering for the GraWIToN project. But moreover I’ll experience a more exotic adventure when I fly across the Atlantic in October for my first time ever as from this year work I could pull together a paper accepted for presentation and publication at SPIE Optifab in Rochester (In New York, not in the UK). It will also be the first time I attend and present at a conference which is outside the Gravitational Waves community. It is not meaningless as one of the purposes of GraWIToN has been to highlight the branching between different fields of research towards a common goal and how the large fundamental research projects can benefit to the private sector even though they are often seen as low return on investment opportunities. Therefore, getting recognition from a different sector and being allowed to present in a conference where most attendants will be coming from the industry is a real achievement to me.  I shall obviously highlight in which frame my work was funded and supervised in a hope to increase the interest of private actors to join such projects.

Speaking of which, as the final point of the project is now in sight, I’ll take the opportunity here to come back on my experience as a Marie Curie Early Stage Researcher and how I see it as a stepping stone for my future career. I’ll stress one more time how grateful I am for all the opportunities I got to travel (I probably travelled more in the past 3 years than in my whole life before), meet people from everywhere and live a wealthy life for my first 3 years in the professional life. At this point it is quite certain that I won’t stay in my host institution after my contract expires mostly because I’m looking forward to go back working in France although I value the experience I had abroad. I haven’t started looking for job opportunities yet because of how uncertain my date of availability is. Of course in an ideal world I’d be able to submit by the end of my contract and be free around February but I’d rather be cautious as I expect it won’t be a straight path. As for where I’ll look for I think I have a strong edge compared to most Ph.D students. And by that I don’t mean skill wise, but because I can make a choice whether to go towards academia or industry with more knowledge on the whys and wherefores than the average. It was something I really valued when I accepted this contract and I’m glad it delivered. So you might wonder to where all that enlightenment leads me. Well for various reasons I’ll probably move away from the academic path and look for a position in the industry or in consultancy. At this point I’ll most certainly lean towards material science to get along with my formation and interests. I don’t especially value it to be in the GW research field but if opportunities arise who knows…

It’s likely the last post that I make here so I’ll once again thank the Marie Curie Programme which funded me, the board of GraWIToN that gave us the opportunity to write here and provided support throughout the project by organizing schools and meetings. And I’ll thank you for following the journey. It was a bit sparse but I hope that it helped picture how the experience was and for those who have the opportunity, maybe encourage you to take part to a similar one.