ESR Projects

ESR1: Advanced atomics & computer control


Sruthi Viswam, Indian, University of Birmingham, Since 1st October 2014

i) Advanced Atom Chamber

Design and construction of a lightweight, UHV compatible, compact and blackbody optimized optical clock chamber for operation with Sr atoms. It will be prepared for the advanced loading and trapping. A thermal enclosure will be designed for the atomics package, which allows control and constancy of temperature to better than 0.1K at the position of the science chamber. Also closed loop magnetic field control will be installed. (WP1)

ii) Setting up a 3D blue detuned magic lattice at 390nm for Sr clock.

A thorough optimization and characterization with respect to different quantum species of Sr, laser polarization etc will be carried out. (WP1)

iii) A full characterisation of 2D-3D MOT system for Sr. (WP1)

iv) Develop frequency stabilisation system (WP4)


SD1.1) Compact science vacuum chamber with controls wrt to temperature and magnetic field.
SD1.2) Efficient and high flux source for ultra cold atoms

ESR2: Transportable Sr optical clock

Jacopo Grotti, Italian, PTB, Since 15th December 2014

i) Development of a compact, low noise interrogation laser system for a transportable ultra precise Sr lattice clock.

This work contains the development of an ultra stable optical reference resonator insensitive to vibrations and ruggedised to withstand transportation. The resonator will be temperature stabilized with the sub mK accuracy at the zero-crossing temperature of the spacer over a broad range of ambient temperatures. To further reduce the sensitivity of the laser system to vibrations, accelerations will be measured and fed forward to the laser control. A compact laser system at 698 nm for interrogation of strontium will be set up and frequency stabilized to the resonator. Vibration, shock and thermal test, simulation realistic conditions, will be performed on the cavity prototype system. The goal is to reach a thermal noise limited instability of 5•10-16 for averaging times between 1 s and 10 s. (WP2)

ii) Metrological characterization of a transportable strontium lattice clock

In order to reach a fractional uncertainty of a transportable strontium lattice clock below 1•10 -16, one needs to take into account the effect of blackbody radiation shifts, magnetic field shifts, lattice-polarization influences, density shift, etc. The ESR will devise tools to characterise these shifts and develop methods for automatic control of these shifts in a transportable clock. Special care will be employed on the evaluation and control of the radiation temperature seen by the atoms, e.g. using distributed temperature probes or in situ infrared sensors. For this work, extensive comparisons between the mobile clock and a stationary clock will be employed at a precision level of 10-17 and below. (WP1)

iii) Establishing limitations of optical frequency comparisons

For frequency comparisons of optical clocks at a level of uncertainty of 10-17, and instabilities of 10-16 at one second, the influence of the femtosecond frequency combs need to be investigated. By comparison of different fibre based frequency combs (Menlo, EPFL, PTB) the influence of the environment (temperature, vibrations) on the performance will be investigated. Suitable parameters will be identified, that can be used as indicators to ensure continuous, unattended high performance operation of the comb for frequency metrology. These methods will be transferred to the operation of short and long range fibre links for frequency and time dissemination.(WP3)


SD2.1) Tested Clock laser system for Sr
SD2.2) Full characterization results report on transportable Sr clock.
SD2.3) Report on the comparison of different frequency combs via fibre link


ESR3: Frequency Comb

Michele Giunta, Italian, Menlo Systems GmbH, Since 1st August 2014

Menlo is working on a program to bring frequency combs to space. The already fixed first launch date of a frequency comb on a sounding rocket is spring 2013. The ESR will participate in this program. Further expansion of this program is currently under discussion with DLR German Space Agency and ESA. Besides this Menlo has implemented a program to continuously improving frequency combs and better understand the fundamental limitations of frequency combs. The ESR will also be involved in this program. Tasks as follow.
i) Preparation and data analysis of a frequency comb flight on a sounding rocket. The ESR will work in the space comb team together with our collaborators MPQ and DLR. Hardware will be set up and tested, after the flight, performance data will be evaluated and suggestions for further flight missions will be made. (WP4)
ii) Pushing the available accuracy from frequency combs to the 10-18 level. The ESR will work on a joint effort with cooperation partners inside this ITN consortium. Existing fibre based combs as well as new micro resonator based combs will the analysed, phase noise and phase drifts will be measured and improvements and refinements will be implemented.(WP3)


SD3.1) September 2013: Report on a frequency comb sounding rocket flight
SD3.2) End of project: report on frequency combs operating at the 10-18 level

ESR4: Microresonator based combs

Eva-Katharina Dietsche, German, EPFL, 1st October 2013 - 31st December 2013

Maxim Karpov, Russian, EPFL, Since 15th March 2015

Frequency combs serve as simple and direct ruler to measure optical frequencies. Conventional combs use mode locked fm lasers. However, there has emerged another novel approach to comb technology which is based on monolithic micro resonators. Another milestone of achieving full octave spanning spectrum enabling f-2f self-referencing scheme has recently been demonstrated. Microresonator based combs can complement conventional combs sources in applications where high repetition rate, high power per comb line, tunability, and bandwidth is critical, such as astrophysical spectrometer calibration, The ESR will seek to investigate and reduce the level of residual phase noise in integrated SiN comb generators and seek to demonstrate multi heterodyne spectroscopy on a chip using this technology. This will be achieved by optimizing the quality factor and dispersion properties of the SiN microcavities. (WP3)


SD4.1) Demonstration of multi heterodyne spectroscopy on a chip

ESR5: Mg optical clock

Nandan Jha, Indian, LUH, Since 1st December 2014

i) Development of methods for precision based metrology and measurements in lattices

  • a) Strategies for establishing a stable and reliable setup for an optical lattice by using an enhancement cavity (WP1)
  • b) Development of efficient loading schemes for the optical lattice (WP1)
  • c) Advanced stabilization schemes for sub Hz lasers (WP2)

ii) Characterisation of Mg optical frequency standard via 70 km long fibre link between the IQ Hannover and the Physikalisch-Technische Bundesanstalt (PTB). The fibre link enables a remote comparison to an optical frequency standard, a hydrogen maser and a Cs fountain clock at PTB. (WP3)

SD5.1) Demonstration of Mg lattice clock

Benjamin Rauf, German, INRIM, Since 15th September 2014

i) High performance ULE cavity - We aim to design a lightweight, low power consuming and vibration low sensitive portable high finesse cavity with frequency stability of σ¬y(τ)=5•10-16 τ<10 s. We plan to use fused silica mirrors (thermal limit 1×10-15) in order to minimise the thermal effects. We will consider several possible designs such as cylindrical, spherical, disc etc. in horizontal as well as vertical configuration. (WP2)

ii) Bosonic 174Yb and fermionic 171Yb high accuracy lattice clock – The clock will be completed and metrologically characterized, with special cares on lattice effects and on Black Body Radiation (BBR) Shift. The clock will be part of the INRIM primary clocks ensemble (two Cs fountains, four Hydrogen Masers) and it will be compared to remote clocks by optical links (see next paragraph) and to an Yb transportable clock within SOC2 project. (WP1)

iii) Optical Fibre link between INRIM and UNIFI- A proposal has been accepted by the Italian Ministry to fibre link INRIM to Florence labs. It will enable two clocks, one in INRIM and another in Florence, to remotely compare against each other. It is a significant step to transfer optical frequencies over such a large distance. (WP3)

SD6.1) Optimised design of a high performance ULE cavity
SD6.2) Demonstration of optical frequency transfer between INRIM and UNIFI

Ruben Pablo Del Aguila, British, UNIFI, Since 1st October 2014

i) Design and set up of ECDL lasers and compact breadboards for repumpers at 679 nm and 707 nm. (WP2)

ii) Setting up of a red detuned 1D magical optical lattice at 813nm, spectroscopy of clock transition and evaluation of systematic frequency shift effects for Sr based clock. (WP1)

iii) Performing comparison between a transportable Sr optical clock and a stationary optical clock. (WP1)

iv) Optical Fibre link between INRIM and UNIFI- A proposal has been accepted by the Italian Ministry to fibre link INRIM to Florence labs. It will enable two clocks, one in INRIM and another in Florence, to remotely compare against each other. It is a significant step to transfer optical frequencies over such a large distance. (WP3)

SD7.1) Report on the clock spectroscopy in 813 nm magical lattice

ESR8: Yb Transportable optical clock

Stefano Origlia, HHUD, Italian, Since 8th September 2014

Chang Jian Kwong, HHUD, Malaysia, from 8th Dezember 2016

i) Optimization of a transportable optical lattice clock using ytterbium (Yb)
The goal of this project is the optimization of an Yb optical lattice clock to achieve a performance which allows for a clock uncertainty of < 5×10-17 and an instability < 1 x 10-15·τ−1/2. The main tasks related to this project concern the operation and improvement of an existing source for ultracold Yb in which bosonic (174Yb) as well as fermionic (171Yb) atoms can be trapped in a resonator-based optical lattice. The current project plan includes- (WP1)

  • First characterization of a 1D optical lattice clock using 171Yb. This very first characterization of the transportable clock will be performed by comparison with a GPS-steered hydrogen maser at the 10-14 level or with an ultrastable cryogenic optical resonator, which is under development in an ESA project, where long-term stability at the 1×10-16 level is projected. The characterization will address systematic effects such as density shifts, blackbody radiation shifts and the lattice polarizability.
  • Investigation of the usability of other isotopes (e.g. 173Yb, 174Yb, 176Yb) for optical lattice clocks. In particular, this includes the measurement of density shifts.
  • Investigation of different optical lattice geometries. This will include lattice traps with different volume and dimensionality.
  • Amendments to the experimental setup, including development of a new experimental control, implementation of advanced laser sources for laser cooling and for the optical lattice, compactification of the optical setup, implementation of improved vacuum components.
  • Full characterization of an Yb optical lattice clock by comparing it to a state-of-the-art stationary clock. It is planned that for this purpose the transportable Yb system will be moved to INRIM at Torino

ii) A compact, transportable frequency metrology unit for an optical clock The goal of this work is to develop the subsystems for stabilizing the frequencies of all lasers of an optical clock, for generating an ultra-stable microwave signal, and for comparing two optical clocks based on different atomic species. The project will also demonstrate successful transportation between and operation in laboratories, e.g. between HHUD, PTB and INRIM. The three corresponding units are the FSS (frequency stabilization unit for cooling and auxiliary lasers, (A), the clock laser (B), and the transportable, stabilized fibre frequency comb (C).
A. The FSS will stabilize 3 lasers for the Yb optical clock: 399 nm (cooling laser, 1 MHz/h), 556 nm (cooling laser, 3 kHz/h), and 759 nm (lattice laser, 1 MHz/h). The FSS will be implemented following a design developed within the EU-SOC2 project, with a small vacuum chamber containing a single ULE-block with two embedded cavities. The waves are delivered from the respective lasers via fibres, pass through fibre microwave phase modulators and are delivered to the cavities. These modulators are driven individually with a phase-modulated microwave signal. The lasers are locked to the cavities on their microwave modulation sidebands, so that changing the modulation frequency allows for a precise tuning of the carrier frequencies with respect to the atomic transitions. (WP2)
B. A compact, robust and transportable clock laser for the Yb clock will be implemented, that will fit on a 60 x 60 cm breadboard, improving on the current design in terms of laser stability, by using a longer ULE cavity with less thermal noise, and robustness. (WP2)
C. The already available transportable fibre frequency comb will be extended by phase-locking it to the Yb clock laser, providing an ultrastable microwave signal for comparison with microwave atomic standards. A comparison between optical standards with different clock laser wavelengths is performed by beating the clock lasers to the stable comb lines. (WP3)

SD8.1) Compact Yb lasers frequency stabilization module (FSS) with fibre incoupling and computer control
SD8.2) Complete high-performance compact 578 nm Yb clock laser system
SD8.3) Reliable transportable optical lattice Yb clock for different bosonic and fermionic ytterbium atoms.

ESR9: Advanced laser systems for space metrology

Slawomir Bilicki, Polish, OP, Since 1st October 2014

Development of a space targeted high performance reference cavity

i) We plan to develop a towards space compatible, compact, thermally stabilized and vibration isolated high finesse ULE cavity for a highly precise Sr clock. Thermal and transport properties will be assessed by finite element calculations and it will be robust to ground transportation. In this context, the ESR will be in close contact with a company having an appropriate experience, namely-EADS SODERN. (WP2)
a) Identification of critical components b) Criticality versus loads and vibrations conditions c) Analysis of weight and dimensions issues d) Analysis of the materials used in the prototype with respect to space environment. (WP4)

ii) Development with PTB of a high-performance compact 698 nm Sr clock laser which will be referenced to the above cavity.

iii) The ESR will have an opportunity to work on two of the best stationary clocks on Sr and possibly on the only existing Hg lattice clock. While working with the clocks, the ESR will be collaborating with teams working on Cs fountain clocks as well as with the team working with frequency comb. (WP1)


SD9.1) A report on the comparison of two Sr clocks and one Hg lattice clock.

ESR10: Advanced systems for Sr space optical clock

William Bowden, Canadian, NPL, Since 1st October 2014

i) We are planning to investigate the shift due to black body radiation (BBR) in a Sr optical lattice clock. We have built a science chamber with specially designed lattice regions in it. These comprise two narrow copper tubes with 3 mm internal diameter and several cm length which should provide well-characterisable blackbody environments determined by the independently-settable temperature of the two tubes. With this arrangement, different blackbody temperatures can be set up for the two tubes in order to experimentally measure the blackbody shift and compare with theoretical data. The BBR shift is one of the major stumbling blocks to reaching ultra high precision. (WP1)

ii) The ESR will also contribute to the evaluation of a frequency stabilization unit (FSS) for Sr neutral or Sr+ ion clocks which comprise a single ULE block with 3 embedded optical resonators. The performance of the separate resonators will be characterised. (WP2)

iii) We have also developed low mass, small volume permanent-magnet Zeeman slowers with zero power consumption which are readily adaptable to various species such as Sr and Yb. The ESR will also have an opportunity to contribute to this activity, if available at an appropriate time during the project. (WP1)


SD10.1) Temperature controlled measurements of BBR shifts.
SD10.2) Compact Sr/Sr+ lasers frequency stabilization module (FSS) with fibre incoupling and computer control

ESR11: Optical clock systems for space

Laura Pedrosa, Spanish, KT, Since 19th January 2014

Kayser-Threde has an outstanding experience in structural design, manufacturing and verification of space structures and test satellites. With the aim of sending and establishing ultra precise sensors based ultra cold atoms, the ESR will analyse and investigate the following aspects-

i) Analyse the effects of space radiation on optical and electro-optical equipment that shall be used for optical clocks (e.g. fibres, lenses, crystals, detectors, …)

ii) Component selection under the aspect of robustness (mechanical, thermal, radiation tolerance). Identification of technological need for further development with regard to the advanced space clock/atom interferometer design and major interfaces (optical access, fibre ports, photo diodes, vacuum adapters to atom source,…).

iii) Breadboarding of clock sub-systems taking into account space engineering aspects. Issues that need to be solved to operate an optical clock in space are the interface between laser systems and the physics package such that actuators for adjustment can be avoided and overall clock complexity/mass/volume is reduced. The combination of sub-systems, the design of robust interfaces including necessary collimation optics between physics package and objective optics / lasers will be envisaged.

iv) Additional tasks (e.g. in-house breadboarding) could be included in case sufficient time of the ESR is available. Currently KT is also working on an ESA project concerning the preliminary design of optical clock subsystems where we intend to employ a PhD student. In line with both projects the ESR could benefit from the parallel projects and exploit the synergies… (WP4)


SD11.1) A report on thoroughly investigated and analysed requirements of space targeted systems

ESR12: Towards transferring optical clock technology to space

Liang Hu, Chinese, KI, Since 7th November 2014

ESR12 will be dedicated to investigate the technical boundary conditions posed by transferring the technology to space. This in particular includes detailed assessments of the electronics with the related power and thermal management, the spatial and weight constraints and robust geometries. The ESR will perform the following specific tasks:- (WP4)

i) Investigation and analysis of the requirement on power and electronics for a space clock or an atom interferometer.

ii) Power distribution, data acquisition & control system.

iii) Input to advanced clock system design optimised with respect to compactness, optimised geometry, optical access and required interfaces compatible with the requirements derived.


SD12.1) A report on thoughly investigated and analysed requirements of space

ESR13: Atom chip

Nephtali Garrido Gonzalez, Mexican, UNOTT, Since 22nd january 2015

Energy Efficient Miniaturised and Integrated Structures (WP1)

i) Layout and design of an atom chip with power consumption below 1 W, no external coils needed and optimised for fast and efficient loading and cooling atoms.

ii) Design of a chip support structure and a vacuum housing in order to accommodate the chip.

iii) Experimental test and optimisation of the full assembly mentioned above.

iv) Loading and investigation of cold atoms from the chip to an optical lattice with at least 104 atoms in the lattice.

v) Test of novel transparent materials. Fabricating atom chips with transparent materials will facilitate the integration of magnetic traps (used as an atom preparation stage and a resource) with optical dipole potentials, especially lattices. Such materials, for example GaN and ITO, will be tested in a clean room in terms of their performance as atom chip conductors. The suitability of the usage of such materials in atom chip trapping and cooling will be tested vi) Detailed investigation of the loss processes, mode control and polarisation properties of optical GaAs waveguide structures. In particular, mode propagation and interference, band edge absorption and polarisation preservation will be analysed. Passive test structures will be fabricated to determine dependencies on material parameters and geometry, including layer thickness, Al concentration and waveguide shape (which affect mode propagation, interference and polarisation evolution). This is very useful for the design of integrated splitters and modulators. (WP1)


SD13.1) Energy efficient (<5W) microchip with at least 104 atoms in the optical lattice.
SD13.2) A report on a thorough test of novel materials such as GaN and ITO for atom chips, and their comparison with gold like reflecting surfaces.

ESR14: Ultra-stable laser and frequency combs

Pierre Brochard, France, UniNE, since 17th July 2015

Atif Shehzad, —, UniNE, since 20th December 2016

i) Development and characterization of an ultra-stable reference optical cavity with improved thermal stability. This work is related to the development of an ultra-thermal enclosure aims at obtaining a high temperature homogeneity of the reference ULE cavity, hopefully improving the short-term stability of the laser up to a timescale of some hundred seconds. (WP2)
ii) All-optical ultra-stable microwave oscillator. Development and characterization of an all-optical ultra-stable microwave oscillator using an optical frequency comb as a frequency divider to transfer the relative frequency stability of an ultra-stable laser into the microwave domain. (WP3)
iii) Assessment of new comb technologies. Study and development of new comb technologies, such as near-infrared diode-pumped solid state lasers or semiconductor mode-locked lasers. (WP3)
iv) Optical frequency transfer in noisy fibers. Investigation of the phase noise induced in the transfer of an ultra-stable optical oscillator in a poorly isolated optical fiber, as encountered along train tracks in the Swiss academic network. (WP3)


SD14.1) Report on fully characterized ultra stable reference optical cavity and ultra stable laser
SD14.2) Report on the characterization of the ultra stable microwave oscillator facilitating optical frequencies to microwave region.
SD14.3) Report on the performance of novel comb technologies.

esr-projects.txt · Last modified: 2017/05/29 09:40 by ur