The LPI project will explore new frontiers in quantum astronomy from La Palma

Observatorio del Roque de los Muchachos / Getty Images
Observatorio del Roque de los Muchachos / IAC
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The Instituto de Astrofísica de Andalucía (IAA-CSIC) in collaboration with the Instituto de Astrofísica de Canarias (IAC), is promoting the LPI (La Palma Interferometer) project whose aim is to make astronomical observations with an angular resolution a thousand times better than that of the Hubble and the James Webb telescopes.

The LPI project has collaboration with various centres of research, and other institutions in Spain, Italy, the nordic countries and Mexic who are working together to build a scientific installation which will be a reference at international level.

Interferometry began in the mid 20th century as a way to overcome the resolution limits of single radiotelescopes. This technique combines signals from multiple antennas or telescopes, achieving sensitivities, and above all resolution which would be impossible with only a single telescope. Until now interferometry has been applied mainly at radio wavelengths, in installations such as ALMA (Atacama Large Millimetre/Submillimetre Array) and in the infrared, with the VLTI (Very LargeTelescope Interferometer) at the European Southern Observatry in the north of Chile. 

The LPI (La Palma Interferometer) project, is proposing a new approach which aims to combine the light from several optical telescopes at the Roque de los Muchachos Observatory of the Instituto de Astrofísica de Canarias (IAC) using the technique of intensity interferometry. This method, as opposed to other types of interferometry, allows the study f correlations between photons in the visible spectrum, opening new possibilities for astronnomicla research. “With individual photon detection technology of the latest generation, developed in Spain, and unprecedented time synchronization, the La Palma interferometer should establish a new frontierin astronomy, letting us explore the universe as never before, with a precision way beyond that of current instruments”, explains Francisco Prada (IAA-CSIC) the Principal Investigator on the project.

The IAA-CSIC, as well as leading the project of the new interferometer on La Palma, is also in charge of the optical design of the SPAD cameras, extremely sensitive devices for detecting light, as well as of the development of the data analysis, contributing actively to the scientific objectives of the project. “Leading the LPI project puts Spain at the forefront of quantum astronomy, with a brilliant future which will allow us to develop the most modern technologies”, indicates Professor Francisco Prada (IAA-CSIC).

Mission and objectives

The LPI project will make astronomical observations using intensity interferometry and the latest generation of SPAD (Single Photon Avalanche Diode) micorchip senors developed at the Micrelectronics Institute at Seville (IMSE CSIC-US).

In addition, the control electronics of these sensors has been designed by the Higher Polytechnic School of the Autonomous University of Madrid (EPS-UAM). Thanks to this innovative technology it will be possible to reach an angular resolution a thousand times better than that of the Hubble and the James Webb Space Telescopes, which will facilitate the study of astronomical phenomena in extreme conditions, such as the accretion discs of black holes, and utra-rapid transitory events.

Furthermore, it can attain a time precision in the picosecond range, corresponding to one million millionth of a second, a time interval so short that light travels only 0.3 millimetres in this time.

The LPI will negotiate its installation in the Roque de los Muchachos Observatory (ORM) integrated into the Singular Scientific and Technical Infrastructures (ICTS) of the Canary Observatories, which is a part of the Instituto de Astrofísica de Canarias (IAC) and is situated in the municipality of Garafía, in La Palma. 

The deputy director of the IAC, Eva Villaver, is sure that “with the technological and instrumental development implied in this project to be sited at the ORM we will be contributing to a better understanding of the universe from one of the best sites for astronomical observations in the world”. She is also very positive about the collaboration between the IAA and the IAC, who share objectives and scientific values which contribute to establishing the leadership of Spanish Astrophysis on the international scene.

If its installation on the ORM is approved, the LPI project will start observing, in an initial phase, using the TNG (Telescopio Nazionale Galileo) which has a primary mirror of 3.6 metres, and the Nordic Optical Telescope (NOT), with its 2.5 m primary. Contact has been established with the management of the Gran Telescopio Canarias, with its 10.4 m primary mirror, and it is planned to start talks with the ING (Isaac Neweton Group of Telescopes,) also on La Palma, to extend the network of telescopes in later phases.

 

Imagen de Google Earth del Observatorio del Roque de los Muchachos en La Palma, que muestra la disposición de los cinco telescopios ópticos del interferómetro LPI. Las líneas de colores indican las líneas de base a implementar en distintas fases, conectando los telescopios GTC, TNG, NOT, WHT e INT. La distancia entre GTC e INT es de 1,5 km. Los telescopios están conectados a través de la red de fibra óptica del Instituto de Astrofísica de Canarias y RedIRIS. En la esquina inferior derecha, se presenta un diagrama a escala de interferómetros como el VLTI y el CHARA. Crédito: Eisenhauer et al.
GoogleEarth image f the Roque de los Muchachos Observatory, La Palma, which shows the layout of the five optical telescopes of the LPI interferometer. The coloured lines indicate the baselines which will be used during different phases, connecting the telescopes GTC, TNG, NOT, WHT, and INT. The distance between the GTC and the INT is1.5 km. The telescopes are connexted via the fibre optical netwoork of the Instituto de Astrofísica de Canarias and RedIRIS. In the lower right-hand corner is a scale diagramof interferometers such as the VLTI and CHARA Credit  : Eisenhauer et al.

 

 

 

A technological challenge

Thanks to the advances of tthe SPAD sensors with ultra-fast readout, and the network of optical telescopes at the Observatorio del Roque de los Muchachos, the LPI project will allow the correlation of signals on extremely short timescales. This will improve the sensitivity of the observatins, and will achieve resolutions of 50 microarcseconds, ( a very small angle indeed) , comparable to the resolution of the Event Horizn Telescope (EHT) but in the visible spectrum. To achieve this will require time synchronization at the 50 picsecond level, a technological challenge which will benefit from the wide experience of the Real Instituto y Observatorio de la Armada (ROA), the ORM and the RedIRIs, the Spanish academic and research network which provides advanced services of communications to the scientific and university communities in Spain.

At the present time, the only operational inteferometer in the visible is CHARA at Mount Wilson, which combines the light from six telescopes of 1 metre primary mirrors with baselines (the distance between two telescopes in an interferometer network) of up to 330 metres. But the LPI, when it is installed on the largest optical telescopes at the Roque de los Muchachos Observatory, with a baseline f 1.5 metres, will be able to observe much fainter objects, and achieve a resolution four times better.  This resolution is equivalent to the angular size of a 1 euro coin seen at a distance of 65,000 kilometres, and opens new possibilities for observing the univers.

Meeting to launch the project

During the meeting at which the project was presented, which took place on November 7th and 8th at theReal Instituto y Observatorio de la Armada (ROA) at San Fernando, Cadiz, presentations were made dealing with different scientific aspectos. They discussed key topics such as the synchronization, and the design of microchip-SPAD sensors, as well as the control electronics. They also discussed the development of the SPAd cameras and the statistical and artificial intelligence techniques needed to analyze the photons which will be observed simultaneously with the network of telescpes of the LPI.

 

Foto del grupo de participantes en el taller de lanzamiento del Interferómetro LPI. En la imagen se observa el Meridiano de San Fernando, que pasa por el ROA, y fue la referencia para toda la cartografía náutica española hasta 1884, cuando en la Conferencia de Washington se estableció como 'Meridiano Cero' universal el de Greenwich / IAA-CSIC
Photo of the group of participants in the launch workshop of the LPI interferometer. In the image you can see the San Fernand Meridian which passes through the ROA  and was the reference for all Spanish naval cartography unitl 1884 when, at the Wahshington Conference the universal “Zero Meridian” of Greenwich was established. / IAA-CSIC

The welcome address was given by Antonio Pazos, the Director of the ROA, Ana Castro, vice-president for Innovation and Knowledge Transfer of the CSIC, Antxon Alberdi, the director of the IAA-CSIC, and Professor Francisco Prada of the IAA-CSIC, Principal Investigator of the LPI, who stressed the scientific and technical relevance of the project. Eva Villaver, the Deputy Director of the IAC participated in the meeting telematically.

There were also present at the meeting personnel of the ROA, of the IAA-CSIC, of the IAC, of the Institute of Microelectronics of Seville (IMSE, CSIC-US) of the EPS-UAM and of RedIRIS, the  Spanish academic and research network which provides advanced communications services to the scientiric and university communities in Spain,; from the Galileo Galieli Foundation of the National Institute of Astrofísica, Ópticaand Electrónica (INAF, TNG) of Italy, of the Nordic Optical Telescope (NOT) of the Gran Telescopio Canaria s(GTC) of the Department of Fundamental Physics of the University of Salamanca (USAL), the Department of Electronics and Computer Technology of the University of Granada (UGR), and of the Instituto de Astronomía of the Universidad Nacional Autónnoma of Mexico (UNAM).

More information

Francisco Prada - f.prada [at] csic.es (f[dot]prada[at]csic[dot]es)