atomic clocks

Discover how quantum mechanics is reshaping our understanding of time, reestablishing computational capabilities, and ensuring the security of sensitive data transmission.  Guest Monika Schleier-Smith is a physicist who says that quantum principles, like entanglement, can make atoms do funny things, such as allowing two atoms to share secrets across great distances. While entanglement opens tantalizing possibilities like quantum computing, there’s still much we don’t know about quantum mechanics. She now uses lasers to “cool” atoms to near motionlessness as a starting point for controlling and proving entanglement, as she tells host Russ Altman on this episode of Stanford Engineering’s The Future of Everything podcast.

Chapter Timestamps:

(00:00:00) Opening Remarks 
Monika Schleier Smith, a distinguished professor of physics at Stanford University, kickstarts the episode by introducing the enthralling world of quantum mechanics.
Russ Altman introduces the episode and welcomes Monika Schleier Smith to discuss quantum mechanics and entanglement. And he encourages listeners to engage with the podcast by rating and reviewing it.

(00:02:50) Quantum Mechanics Fundamentals

Monika provides insights into the fundamental principles of quantum mechanics, including the concept of quantum uncertainty.

(00:04:22) Embracing Entanglement 

The episode delves into the concept of entanglement, highlighting its non-local properties and the intriguing correlations between particles.

(00:06:55) Initiating Quantum Entanglement 

Monika explains the initial interactions required to establish quantum entanglement between particles. Explore the challenges in preserving entanglement and the impact of quantum measurement.

(00:10:12) Laser-Cooled Atoms in Research 

Monika Schleier Smith sheds light on her lab's laser-cooled atoms research and their vital role in entanglement studies.

(00:11:39) The Doppler Effect and Slowing Atoms

Monika explains the Doppler effect and its role in slowing down atoms using laser beams. Russ Altman connects the Doppler effect to everyday experiences, like the sound of approaching vehicles.

(00:13:04) Tracking and Holding Atoms

Monika describes the next steps in their experiments, involving tracking and holding well-controlled atoms in a vacuum. Russ Altman mentions the challenges of maintaining atoms at low temperatures and in isolation.

(00:14:49) Getting Atoms to Talk

Monika explores the need for entanglement and how it involves making atoms interact. Different approaches, including using Rydberg states and optical resonators, are mentioned.

(00:16:17) Leveraging Light as a Messenger

Monika introduces the concept of using light to convey information between atoms. The discussion includes optical resonators and controlling interactions on different length scales. Russ Altman jokingly mentions the potential size of the lab.

(00:16:32) Preserving Entanglement

Monika highlights the challenge of preserving entanglement and preventing information leakage to the outside world. The importance of maintaining secrecy for entangled states is emphasized.

(00:17:34) Proving Entanglement

Monika explains the need for proving entanglement, distinguishing it from classical correlations. She mentions John Bell's contributions to the theory of proving entanglement. Russ Altman seeks clarification on classical correlations.

(00:20:13) Measuring Incompatible Observables

Monika outlines the measurement of incompatible observables as a way to prove entanglement. The discussion touches on the concept of spin for atom measurements.

(00:22:19) Quantum Computing Potential 

The conversation shifts to quantum computing, where Monika discusses how quantum bits (qubits) can provide computational advantages over classical bits, paving the way for solving complex problems like drug discovery and material science.

(00:28:15) Quantum Communication Secrets 

Monika sheds light on quantum communication's ability to secure data transmission by leveraging the principles of entanglement and quantum error correction.

 (00:32:39) Conclusion & closing

 Russ and Monika wrap up their enlightening conversation, emphasizing the ongoing pursuit of quantum knowledge and technology.

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Atomic clocks are the most precise time-keepers we have.

But that doesn't mean they can escape the timey wimey effects of gravity. 

In this episode of Great Moments in Science, Dr Karl explains how this enables super-accurate clocks to not just measure time, but height as well.  

Although time may not materially exist, most of us still measure it out using clocks and calendars. From the creation of days to the atomic clock, this episode explores how the abstract concept of time became a countable “reality” — and why metric time worked its way to the heart of Western society.

This episode in brief:

1. Mapping calendrical time | 03:15

The countable time we use in our everyday life is a social construction. This section takes a look at how different cultures divided the abstract concept of time into days, weeks, months and years. We consider the mathematical limitations of basing units on environmental cues like the Earth’s rotation. From the 10-day weeks of ancient China to the alternative names for months in modern Turkmenistan, we explore how our calendars are as much cultural creations, as empirical tools.

2. The evolution of clock time | 10:55

This section explores the heritage of smaller units for tracking time — like hours, minutes and seconds. We trace the colourful history of time keepers, from water clocks and obelisks to the complex machinery of drive weights, pendulums and vibration. We see how our most precise timepiece — the atomic clock — still falls victim to the inconsistencies of nature; that the quest for a mathematically pure time will always be at odds with the realities of our material universe. 

3. The global standardization of time | 18:10

Ever wondered where time zones came from? How the US settled on its four standard time belts? Or when the global organization of time began? This section explains all. It lays out the local origins of time standardization, through to the governmentally-sanctioned version of universal clock time we use today. We consider the pressures of local organization, industrialization, expanding transport and communications networks in the drive to create a coordinated social framework for time.

4. Living with metric time | 23:40

While we may run our lives according to clocks and calendars, that’s not to say we have an easy relationship with them. This section takes a closer look at the social implications of metric time to consider what it means today. Historian Paul Glennie deconstructs the disciplinary narrative of clock time — with its ties to 19th century industrialism — to show why it only represents one part of the social time picture. Using more contemporary examples, we explore what metric time means for our consumer services, personal aspirations and social etiquette.