#quantumclocks

Dr Dana Anderson The Founder and Chief Science Officer of Infleqtion, Dr. Dana Anderson, has been elected to the National Academy of technical (NAE), a top technical honor. This induction honours Dr. Anderson's optical quantum engineering of ultracold atoms discovery, which underpins Infleqtion's commercial technology.

A new theoretical framework could allow scientists to measure gravitational time dilation, one of Albert Einstein's most challenging predictions, on a lab bench. A group of researchers used entangled multi-photon quantum clocks and vertically split quantum memory to discover relativistic effects at a few meters scale, which could help reduce the gap between general relativity and quantum mechanics.

What's Gravitational Time Dilation?

Gravitational time dilation occurs when the local gravitational field strength shifts time. According to Einstein's general theory of relativity, a clock near a large body, where gravity is stronger, ticks slower.

This effect has typically required enormous distances or delicate technology to detect, but atomic clocks on mountain summits—not at sea level—have documented and validated it. It also ensures GPS satellite accuracy. The fundamental challenge for decades has been observing relativistic effects in quantum physics, which governs subatomic matter.

A New Method: Quantum Clock Interferometry A study by Mustafa Gündoğan, Roy Barzel, and Dennis Rězel from Humboldt-Universität zu Berlin and Mün Bremen has proposed a memory-assisted quantum clock interferometer. This technology uses photon intrinsic states as quantum clock “ticks” instead of two physical clocks.

Two suitable times are superimposed in the experiment. A quantum particle can be in several states at once. Using frequency-bin entangled photons in two vertically separated quantum memory, the researchers can make the device "experience" two gravitational potentials simultaneously.

Key components of this experiment include:

Vertical Separation: Memories' gravity factors vary with height. Quantum Memories: Rubidium and caesium atoms store light frequency components as collective spin waves. Hong-Ou-Mandel (HOM) Interferometry: This quantum optical technology collects photons and interferes with them to reveal minute phase shifts caused by different time frequencies. Read Quantum Fermionic Antiflatness Quantifies Non-Gaussianity.

Entanglement amplifies the signal This study's biggest novelty is using entangled multi-photon states to boost the signal. Conventional interferometry has a negligible gravity-induced phase shift. The scientists observed that adding 2N frequency-entangled photons increases the proper-time dependent phase by a factor of N.

For time, this amplification is a biological microscope. By accelerating the interference signal's collapse and rebirth, it highlights the minute temporal difference. The number of photons (N) increases measurement sensitivity, allowing time dilation to be detected at much smaller height variations than previously thought.

To Kilometres to Metres: Laboratory Reduction Photonic techniques to time dilation required free-space transmission across tens of kilometers. Quantum memories change the game. By storing photons for a specifically defined duration (τ s), the "clocks" can detect time differences without long distance travel.

Using realistic memory lifetimes and efficiency, the team's models predict an interference pattern collapse with sub-second storage periods and a height difference of 10 to 100 meters. In addition, advanced rare-earth ion and alkali memory pairings could lower the required height to a few meters. In a typical lab, this allows exceedingly accurate general relativity tests.

Quantum-Relativity Interface: Why It Matters This research tests physics, not merely ways to build a clock. General relativity and quantum mechanics, the two basic assumptions of modern physics, are incompatible.

Fundamental tests: The framework lets researchers study gravity's influence on quantum superpositions. It examines whether time dilation can cause quantum entanglement and coherence. Entanglement can be used to overcome classical measurement constraints in quantum metrology. This aids precise navigation, modern timekeeping, and geodesy, which charts the Earth's shape and gravity field. Future iterations of this study may use vertical scanning to measure spacetime curvature.

Tech Obstacles and Future Even with a solid theoretical basis, experimental issues remain. Generating and managing many entangled photons requires precision. To avoid data loss or “decoherence” from environmental vibrations and noise, quantum memory must be very effective.

However, the authors note that exploratory efforts to achieve the requisite entangled states have been made. A proof-of-principle demonstration is likely in the next few years due to tremendous technological improvement in rare-earth ion-doped crystals and alkali atom systems.

Infleqtion and Safran to Protect Critical Infrastructure from GPS Failure

The Safran Company

Infleqtion, a neutral-atom quantum technology pioneer, and Safran Electronics & Defence announced a groundbreaking strategic cooperation for global security and telecommunications. This alliance will develop and implement next-generation quantum precision timing solutions to protect global infrastructure against GPS threats. Political conflicts have made Global Navigation Satellite Systems (GNSS) vulnerable, a serious national security concern. This collaboration meets the defence, aerospace, telecommunications, and national security industries' need for GPS-independent time.

No More GPS Dependence

GPS signals are the main synchroniser for modern infrastructure. These signals are weak and more susceptible to spoofing and jamming by foes, which might disrupt power grids, financial trading systems, and military communications. The Infleqtion Safran cooperation uses quantum physics to eliminate this “single point of failure”.

In contrast to mechanical oscillations or microwave transitions, Infleqtion's quantum optical clocks exploit neutral atom's greater optical transition frequency. This technology improvement allows for stability and accuracy several orders of magnitude more than envisaged in the business. The cooperation develops a dependable satellite-based timing alternative to ensure important operations may continue even when GPS signals are challenged, denied, or intentionally hampered.

A Validated Global Market “Timing Bundle”

This relationship is based on a confirmed “timing bundle” that combines Safran's industry-standard synchronisation technology with Infleqtion's Tiqker quantum optical clock. This integrated solution uses Safran's White Rabbit and SecureSync technologies and Infleqtion's atomic technology's high-precision “source”.

SecureSync is the most reliable synchronisation option, according to many. Together, they create a powerful “holdover” with the Tiqker clock. This means the quantum clock may maintain immaculate synchronisation for lengthy periods of time after a GPS signal loss, providing reliable timing for modern sensors and rapid data networks.

White Rabbit, an Ethernet-based synchronisation technique, may also give huge fibre networks sub-nanosecond accuracy. By combining these technologies, the cooperation delivers an end-to-end solution for data centres and big telecommunications hubs that need synchronised time across miles of infrastructure.

Strategic context and executive vision

Both organisations' leaders have pitched this collaboration as a commercial plan to protect the world's most critical systems. The relationship is crucial to developing safe and widely available timing capabilities worldwide, according to Infleqtion CEO Matt Kinsella. Alexandre Lenoble, Head of GNSS & time at Safran Electronics & Defence, says asserted time is a strategic advantage in mission-critical scenarios.

After aggressive strategic initiatives in 2025, Infleqtion released this declaration. The company obtained $100 million in Series C funding and partnered with Voyager Space to provide quantum clocks to the International Space Station and other commercial space stations like Starlab. Safran's leadership in PNT robustness is strengthened by the collaboration. Safran has also partnered with QinetiQ to provide anti-jamming capabilities for the UK Armed Forces to stay ahead in the PNT market.

Impact on Key Sectors

Global availability of the confirmed timing bundle is scheduled in the first quarter of 2026. One of the first “plug-and-play” quantum computing systems for commercial and defence use, Safran's global network will supply and service it. Partners have identified several significant markets that will benefit from quantum-powered defence:

Defence and Aerospace: Ensuring command centres, planes, and naval vessels in contested zones have uninterrupted time.

Providing exact synchronisation for next-generation fibre networks like 6G.

Protecting synchronised power grid switching from cyberattacks and electronic interference.

Finance: providing millisecond timestamping for high-frequency trading and legal compliance.

To conclude

Quantum Clock Measurement Costs Rise: Reading a Nanoscale Timer Takes a Billion Times More Energy Than Running It

Quantum Clock Measurement Costs

A groundbreaking Oxford University study revealed a surprising insight regarding quantum timekeeping thermodynamics: Measurement uses more energy than operation for quantum clocks. Reading the clock and converting its feeble signals into data can require up to a billion times more energy than the clock mechanism.

This discovery will impact quantum technology, notably sensors and navigation systems that use accurate and energy-efficient internal clocks.

Energy Mystery at Quantum Scale

Timepieces like atomic oscillators and pendulums use irreversible physical processes. At the quantum level, irreversible processes are weaker or nearly nonexistent, making exact timekeeping harder. The thermodynamics of quantum clocks is mostly unknown.

Any clock that keeps time generates entropy and heat, per the second law of thermodynamics. These are usually caused by irreversible processes like springs winding down or gravity pulling sand grains. However, co-author Florian Meier suggested a nanoscale clock with reversible “ticking” motions that cause no entropy. With each quantum dot hop, an electron may record a tick. This seemed to contradict clocks' need to generate entropy and expend energy.

Building the Microclock

To solve this dilemma and calculate the thermodynamic cost of sustaining time at the quantum scale, researchers directly studied the cost of measurement.

The team, which included Technische Universität Wien and Trinity College Dublin, developed a tiny clock using two nanoscale regions dubbed double quantum dots. This device employed single electrons to jump between zones, so each electron leap was a clock "tick". The electrons on the left and right dots (states L and R) and three unoccupied states (state 0) comprised the clock cycle.

Radio waves and small electric currents were used to track these quantum ticks. The sensors were crucial in both situations, translating faint quantum signals (electron leaps) into classical data. This is called the “quantum-to-classical transition”.

The Entropic Cost of Watching

The researchers meticulously calculated the measurement device and quantum clockwork (double quantum dot) entropy, or energy dissipated.

A shocking difference was found. The clock mechanism used much less energy than reading the clock and recording its tiny signals. It was found that the quantum clock's cycle produced a billion times less entropy than monitoring and recording the clock signal. Co-author Vivek Wadhia says the entropy created by amplifying and monitoring the clock's ticks is a simple thermodynamic cost that has often been overlooked.

This massive entropy creation resolved the contradiction. Even if the quantum ticking motion produces zero net entropy, the sensor dot creates entropy during measurement, hence the second rule of thermodynamics is not broken.

Future Quantum Design Focus Shift

This discovery disproves the idea that quantum mechanics' measurement cost can be trivialised. Quantum clocks were intended to minimise timekeeping energy costs, however senior scientist Professor Natalia Ares found that measurement energy exceeds clockwork energy.

The paper suggests shifting focus to better quantum clocks. Instead of finding better quantum systems, researchers should develop smarter, energy-efficient tick measurement methods. Ares expects the experiment to reveal ways to improve quantum technologies. Quantum electrical systems expert Edward Laird acknowledged that the mechanism between a clock's ticking and its classical ticks must be included in any correct energy cost analysis.

Measurement shapes time

Beyond technological implications, the work presents major physics theoretical questions, including time directionality.

The findings link information science and energy physics by showing that measuring beyond the clock drives time forward and makes it irreversible. Time is directed by observation.

The researchers propose that this energy imbalance may be beneficial over time. Measurements with greater energy could provide a better understanding of the clock's operation by logging every minor change instead of just a tick count.

AUKUS Trial Successfully Tests Australian Quantum Clocks for GPS-Independent Defence Operations

With the completion of prolonged trials in the US of world-class quantum technology clocks produced in Australia, the AUKUS Pillar II collaboration and linked defence capabilities have advanced.

For six weeks, AUKUS partners in Washington, D.C. extensively examined four Australian quantum clocks. The University of Adelaide and QuantX Labs contributed two clocks. Clocks were evaluated for military navigation and communication systems in different climates.

For quantum clock development, the Albanese government invested $2.7 million in AUKUS Pillar Two capabilities. QuantX Labs had previously received about AUD 2.7 million from the Australian Government to manufacture military pocket quantum photonic atomic clocks. Project partners include the Defence Science and Technology Group (DSTG) and independent academic and industry partners.

An edge in pressure

Quantum clocks detect GPS spoofing and jamming, synchronise communication networks, and provide reliable position, navigation, and timing (PNT) when traditional navigation signals are lacking.

By adopting this technology into AUKUS partners' armed forces, the Australian Defence Force (ADF) can perform better in tough GPS-less situations. Modern military systems depend on GPS signals for timing, navigation, and synchronisation, so maintaining these capabilities if GPS is corrupted, falsified, or jammed is crucial.

In denial situations or underground, urban, or underwater operations, defence troops' ability to execute autonomous operations with safe timing and navigation provides a tactical and strategic advantage. Clocks can replace satellite-based timing systems reliably.

Minister for Defence business Hon. Pat Conroy MP says Australian enterprise has led quantum technology. He said that by using emerging technologies and sharing knowledge and expertise, the partners are establishing AUKUS Pillar II capabilities faster than any single country could.

Precision and Australian Tech

Australia is a global leader in quantum technology due to its top quantum researchers and technologists. Australia's proprietary, sovereign quantum clock technology enhances other countries' advanced portable clocks.

Optic atomic clocks use rubidium or ytterbium atoms in low-pressure gas cells probed by lasers to provide ultra-stable time signals. In tests, their precision was “many orders of magnitude” better than normal GPS time signals. In one-second measurements, they are 20–200 times more accurate than international norms.

The Australian partners created novel technology. The University of Adelaide's portable optical atomic clock, the only one going commercial, uses warm Ytterbium vapour. In the meantime, QuantX is employing Rubidium to construct a portable optical atomic clock based on proprietary, patented Australian intellectual property and a two-color, two-photon technology. These independent technologies that use new elements' unique properties in ways that aren't commercialised elsewhere were developed by ongoing government investment through the Defence Science and Technology Group.

Integration and deployment

The 2024 National Defence Strategy and Defence Innovation, Science, and Technology Strategy say quantum technology is crucial to the ADF's future. The successful experiment results will be shared with AUKUS partners to guide future defence actions using quantum clocks.

Clocks are essential to quantum science and sensing initiatives like quantum radar and quantum communications. Military systems like communications, radar, and networked sensors depend on time, therefore enhancing the timing backbone boosts capacity and endurance.

QuantX and the University of Adelaide launched a USD/AUD 13.8 million initiative. This effort aims to progress technologies from prototype to deployable systems by enhancing dependability and reducing SWaP for field and mobile use. QuantX promises a transportable test and measurement system by early 2025.

Banks, telecommunications, and space missions that require precise timing could benefit from these clocks.

Quantum Clocks

NIST researchers have developed an atomic clock that can measure time to the 19th decimal place, a remarkable achievement in time measurement. After 20 years of hard labour, this record is 41% more accurate than the previous one.

Trapped aluminium ions make the “quantum logic clock” 2.6 times more stable than earlier ion clocks. The July 14, 2025 publication of this finding in Physical Review Letters contributes to global efforts to precisely redefine the standard second and may lead to new scientific and technological uses.

Understanding NIST and QLC

NIST, a US federal body, advances measuring science, standards, and technology. Scientific progress depends on its metrological work, which measures frequency and time.

This greater accuracy is based on quantum logic spectroscopy. The clock uses an electrically charged aluminium ion due of its high-frequency “ticking” rate and resistance to temperature and magnetic fields. Atomic clocks require direct laser probing and cooling of aluminium ions, which are notoriously difficult.

The researchers built a “buddy system” of magnesium and aluminium ions to avoid this. Lasers can control magnesium, however it has poor timing qualities compared to aluminium. By mediating, the magnesium ion helps the aluminium ion cool and read out its quantum states through motion. This intricate coordination lets the aluminium ion “tick” unaltered.

Surmounting Major Engineering Challenges

To attain this unequalled accuracy, numerous interdependent systems have to be meticulously optimised, overcoming key engineering barriers that had limited ion clocks.

Redesigned Ion Trap: Overcoming "excess micromotion," small, unintended motions of the ions inside the trap that vary their ticking rate and affect clock accuracy, was difficult. Additional fields from electrical mismatches in the earlier trap design disturbed ions. The scientists placed the trap on a thicker diamond wafer by carefully rebuilding the trap and changing the gold electrode coverings. This intervention reduced electrical resistance, adjusted electric field imbalances, and reduced disruptive ion motions to preserve the aluminium ion's ticking rate.

Titanium Vacuum Chamber: Background gas contamination, notably residual hydrogen gas, prohibited prior ion clocks from working by diffusing from steel vacuum chambers and colliding with ions. For this, the researchers designed the vacuum chamber from titanium, which outgasses less. This crucial enhancement cut leftover hydrogen gas by 150 times, extended operational endurance from 30 minutes to days, and standardised ion monitoring conditions. Ultrastable Laser Integration: JILA, a joint NIST-CU Boulder institute, helped increase precision and stability. A world-stable laser from Jun Ye's lab was employed. This ultrastable laser was supplied to NIST's frequency comb over 3.6 km via fibre optic cables. This process “transferred” JILA laser stability to the aluminium clock laser, allowing comparisons. Limiting quantum fluctuations during measurement reduced the time needed to achieve 19-decimal place precision from three weeks to 1.5 days. It also allowed researchers to study ions for a second instead of 150 milliseconds.

In addition to these fundamental advances, significant efforts were made to characterise and decrease minute effects like thermal fluctuations, electromagnetic interference, and vibrations, which lowered accuracy.

Wide-ranging uses and prospects

Due to its enhanced stability and reduced measurement time, this new clock can be used for many purposes beyond precise timekeeping.

This development aids global efforts to define the standard second. Precision Geodesy: The clock's accuracy allows for unparalleled resolution in studying Earth's geodesy—its gravitational field, form, and orientation. Detecting minute time shifts that represent minor mass distribution changes may help us comprehend plate tectonics, glacier movement, and groundwater oscillations.

basic Physics Investigations: The clock allows for the search for basic constant changes outside the Standard Model, which requires precise timing. The shorter average time needed to acquire accuracy allows longer observation periods and greater sensitivity to changes.

Quantum Technology Testbed: The clock's upgrades make it a better testbed for quantum physics experiments and quantum technology equipment. Rapidly analysing and changing the clock's performance allows high-precision, portable timekeeping, which may affect satellite navigation and secure communications.

Intro to quantum clocks

Quantum clocks use laser cooling to confine single ions in electromagnetic ion traps. NIST scientists constructed a clock 37 times more accurate than the international norm in 2010.

A New Quantum Clock Has Unprecedented Precision with Less Energy. Scientists revealed a quantum clock with unsurpassed accuracy and low energy usage, advancing precise timekeeping. This device challenges scientific views about the inherent cost of entropy in exceedingly accurate time measurements. It could revolutionise quantum computing and other high-precision technologies, as well as science.

Enduring Precise Timekeeping Challenge

Physicists have spent years developing clocks that measure little quantities of time accurately. Quantum clocks use quantum physics to increase precision. Entropy and energy use have always increased with clock accuracy. This energy cost has historically included accurate timekeeping.

Traditional and quantum clocks count irreversible events like atoms hopping energy levels or pendulum swings. Each “tick” loses a tiny amount of energy as heat, increasing entropy. Double precision has typically doubled entropy in these systems. The one-to-one trade-off was considered a shortcoming of timekeeping technology until recently.

Paradigm Change: Almost Dissipation-Free Quantum Clock The 2023 Quantum Thermodynamics Conference in Vienna inspired a global community of scholars to carefully investigate these presumptions. Their unique approach allows quantum processes to run continuously and coherently, like a wave, to save energy.

Not every tick is measured by this unique quantum clock. Instead, coherent quantum transport lets quantum excitations small energy packets travel through a system easily, monitoring the entire temporal flow. According to researcher Marcus Huber, this allows a resolution-precision trade-off “in a new and genuinely quantum manner,” similar to an hourglass where waiting for sand to fall results in more accurately resolved time units.

This cohesive process without intervening measurement or interruption prevents entropy from being produced with each tick. The linear relationship between entropy and accuracy is broken, and entropy increases much more slowly as precision increases, suggesting high efficiency. The clock's architecture uses quantum many-body systems, in which particles form coordinated, wave-like patterns, to enable precise control without thermodynamic costs.

Impacts on Future Technologies

This development improves precise timekeeping, which quantum technologies require. Current atomic clocks have little energy dissipation, but this will change. Florian Meier, the lead researcher, compared it to traditional computing, where heat dissipation, previously considered minor, is now a major concern for data centres that manage massive amounts of data. Dissipation may also limit high-precision clock applications.

Importantly, this strategy cleverly uses quantum phenomena like coherence transfer to lower entropy to a substantial degree, but it cannot completely eradicate it since thermodynamics forbids it. Its energy-efficient design could power additional quantum machines like sensors and computers, making them more energy-efficient than timekeeping. This might boost space exploration, telecommunications, which require precise synchronisation, and even national security and global positioning on a military level.

Theory to Reality: The Future

The researchers initially validated their unique approach using theoretical models. Workable prototypes are being made. Chalmers University of Technology is prototyping a superconducting circuit. Lab testing of energy-saving advantages requires prototypes. The findings of this major study were reported in Nature Physics.

The Future of Time and Tech