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COMPLETE SOLUTIONS FOR QUANTUM APPLICATIONS
How Menlo Systems ' Optical Frequency Combs and Ultrastable Lasers Enable the Second Quantum Revolution
Quantum technologies are driving a new era of innovation by exploiting quantum physics for real-world applications. Their ability to measure, compute, and communicate with unprecedented precision makes them essential for tackling today’ s most complex scientific and technological challenges. Particularly impactful is quantum sensing, harnessing fragile quantum states of atoms, ions, or photons as ultra-sensitive probes of their environment, enabling breakthroughs in navigation, geodesy, and tests of fundamental physics.
To realize these capabilities, researchers need tools that combine absolute stability, coherence, and reproducibility. From quantum simulators, communication, and computing to atomic sensors and metrology, precisely stabilized light is needed to manipulate atoms and ions, define timing and phase relationships, and establish coherent links between quantum systems.
This is where photonics comes in: optical frequency combs are mode-locked pulsed lasers whose spectrum consists of thousands of evenly spaced, phase-coherent lines. When locked to an ultrastable reference, the combs inherit this stability and transfer spectral purity to other wavelengths at the 10 −18 level, enabling precise probing of atomic transitions.
Menlo Systems has served the optical community with highend optical frequency combs for nearly 25 years and provides a fully integrated, commercial solution for quantum and timekeeping applications: the FC1500-Quantum. The system combines an optical reference and an ultrastable frequency comb with several continuous-wave( CW) lasers for atom cooling, repumping, and addressing narrow clock transitions in atoms or ions. Low phase noise of the comb-disciplined lasers ensures the phase coherence required for precise state manipulation. Laser light can be fiber-delivered to the physics package, simplifying integration with vacuum systems and optical setups. Acting both as a reference for all lasers and as the spectral bridge linking optical and microwave domains, frequency combs are the heart of modern quantum laboratories [ 1 ].
A showcase example of the FC1500-Quantum in action is Fermilab’ s MAGIS-100( Matter-wave Atomic Gradiometer Interferometric Sensor) [ 2 ] project, which aims to explore fundamental physics through atom interferometry over a 100-meter vertical baseline. Here, clouds of ultracold strontium atoms are launched in free fall while laser beams, stabilized by the FC1500-Quantum, act as beam splitters and mirrors for matter waves. Several watts of sub-hertz light at 698.4 nm are collimated along the baseline. The system’ s ultrastable frequency and phase coherence are critical for this quantum sensor, which could probe ultralight dark matter, test the equivalence principle and pave the way for future gravitational wave detectors.
▲ The atomic transitions in Strontium( Sr) atoms with the ultranarrow clock transition at 698.4 nm( upper part). A commercial FC1500-Quantum system for optical clock applications contains an ultrastable laser transferring its spectral purity onto an optical frequency comb and all other lasers which are also locked to the comb( lower part).
Another example of frequency-comb-aided quantum-enabled precision is found in optical atomic clocks, which are poised to redefine the SI second. Unlike the current standard cesium clocks, which are based on transitions at roughly 9 GHz, optical clocks leverage the stability and accuracy of ultra-narrow atomic transitions in the optical range, typically hundreds of THz. Frequency combs form the core of such systems and act as clockworks, counting trillions of oscillations. These state-ofthe-art clocks allow for a precision of 10 −18 [ 3 ], corresponding to an error of 1 s in 15 billion years. With collaborations like MAGIS-100 and the Boulder Atomic Clock Optical Network( BACON) [ 4 ], Menlo Systems is pushing the boundaries of quantum sensing and metrology.
REFERENCES
[ 1 ] M. Giunta et. Al.: Nat. Photonics 14( 2020), 44 – 49 [ 2 ] Mahiro Abe et al.: Quantum Sci. Technol. 6( 2021) 044003 [ 3 ] E. Oelker et al.: Nat. Photonics 13( 2019), 714 – 719
[ 4 ] Boulder Atomic Clock Optical Network( BACON) Collaboration: Nature 591( 2021) 564 – 569
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