From: mk_thisisit
The field of quantum physics has made remarkable strides in controlling matter at its most fundamental level, particularly through the manipulation of individual atoms and ions at extremely low temperatures [00:05:30]. These experiments push the boundaries of what is possible, creating the coldest places known in the universe on Earth [00:00:25].
The Coldest Places in the Universe
While CERN hosts some of the highest temperatures, approaching those of the Big Bang’s first fractions of a second [00:52:00], laboratories in Warsaw and other locations conducting experiments with cold atoms are home to the coldest places in the universe [00:00:25]. These temperatures are de facto a billion times less than room temperature [00:00:28]. The pursuit of absolute zero temperature can be compared to the pursuit of the speed of light: both are theoretically unattainable but can be approached arbitrarily closely [00:10:36]. Naturally, such low temperatures do not occur and require significant effort to achieve [00:12:02].
Breakthrough in Cooling Single Ions
A significant scientific achievement involves cooling a single ion to record low temperatures, close to one microKelvin [00:37:00]. This temperature is a billion times lower than typical room temperature [00:07:45]. This feat was accomplished in cooperation with experimental groups in Amsterdam and Freiburg [00:04:41]. The method involved catching a single ion in a complex trap and immersing it in a gas of very cold atoms [00:06:06]. The ion was then cooled through collisions with these ultracold atoms [00:06:16]. Such a cold ion had never been observed before [00:06:25].
Quantum Effects at Ultralow Temperatures
At these extremely low temperatures, quantum effects become readily apparent [00:07:56]. Unlike normal conditions where classical mechanics (Newtonian physics) suffices to describe systems like airplanes or cars [00:08:22], individual atoms and molecules at very low temperatures move extremely slowly, approaching the limits of minimum energy [00:08:38]. This leads to quantization, where the world is no longer continuous, and only discrete, specific values of energy are allowed [00:09:08]. This discreteness is a fundamental property of our universe, described by the laws of quantum mechanics [00:09:56].
One notable consequence is the ability to observe and induce quantum superposition, where elementary particles can be simultaneously in multiple states or places [00:12:55]. For a single ion, creating a Schrödinger’s cat state, where the ion is simultaneously in two places or states, is relatively easy [00:13:03]. While direct observation of superposition is impossible due to wave function collapse upon measurement [00:25:00], its effects are real and measurable [00:25:53].
Manipulating Atoms and Chemical Reactions
Physics has developed the ability to manipulate individual atoms at will [00:05:30]. For neutral atoms, this was achieved earlier, but single ions pose a greater challenge to cool to the lowest possible temperatures [00:05:50].
Techniques for Catching and Observing Ions
- Vacuum Chambers: Experimental systems are isolated from the outside world using high-quality vacuum chambers [00:21:50].
- Optical Tweezers: Laser beams are used to create “optical tweezers” or traps [00:21:45]. The intersection of two or three laser beams creates areas of higher light intensity where individual atoms can be caught [00:23:09]. Sometimes, many atoms are produced, and then all but one are removed [00:23:21].
- Magnetic Fields: Appropriately shaped magnetic fields can also create traps to catch atoms [00:22:19].
- Ionization: For ions, it’s easier to simply ionize a single atom, which can then be caught and used [00:23:26].
- Photographing Ions: Single ions can be photographed by reflecting photons from them [00:23:37]. The image, often a single pixel or a blur corresponding to the wave function’s shape, shows the probability distribution of finding the ion [00:24:12].
Quantum Control of Chemical Reactions
At ultralow temperatures, external factors like electric or magnetic fields can drastically influence chemical reactions, dominating over thermal effects [00:13:43]. This allows for the acceleration or deceleration of chemical reactions by a million times [00:13:59]. Research in this area, in cooperation with Nobel Prize winner Professor Wolfgang Ketterle, has explored how magnetic fields change reaction rates in mixtures of atoms and simple molecules at very low temperatures [00:26:57].
The ultimate goal is to understand chemical reactions at an extremely detailed level, which could eventually lead to increased efficiency in industrial synthesis processes [00:28:38]. This involves simplifying systems to their most basic components, gaining full understanding, and then applying this knowledge to more complex systems [00:29:16]. Recent work also investigates subtle effects like the coupling between electron spin and molecule rotation in chemical reactions at low temperatures [00:29:52].
Broader Implications and Applications
The ability to cool single ions and manipulate them opens doors to various fundamental and applied research areas:
Testing Fundamental Laws of Nature
Ultralow temperatures reduce noise, allowing for much more precise measurements of atoms’ and molecules’ internal, fundamental properties [00:15:20]. This precision can link to even more fundamental laws of physics [00:15:57]. For instance, ultracold molecules are used to measure the electron dipole moment [00:16:01]. While the Standard Model predicts an extremely small or zero dipole moment, some string theories predict a larger one [00:16:17]. Measurements at ultracold temperatures have already ruled out several string theories [00:16:25]. A non-zero measurement would represent a significant breach in the Standard Model, opening new avenues for particle physics [00:17:08].
Quantum Technologies and Computers
The precise control of individual atoms and molecules at ultralow temperatures is essential for building quantum computers and advanced sensors [00:21:25]. The development of quantum computer technology based on cold atoms is currently experiencing a renaissance [00:40:43]. While cold ions have always been part of the discussion for quantum computing, neutral cold atoms were considered a “Cinderella” technology for decades [00:40:55]. However, in the last five years, technologies based on cold atoms in optical lattices (light crystals created by interfering laser beams to form light maxima and minima, where atoms are caught [00:30:44]) and optical tweezers have shown immense potential, possibly surpassing other quantum computing architectures [00:41:06]. This involves using Rydberg excitations in these optical traps [00:42:10].
Exploring New States of Matter and Dark Matter
Ultralow temperatures enable the separation of specific effects and strengthen quantum phenomena [00:38:00]. This allows for the creation of quantum states of matter that are too sensitive to thermal noise at room temperature [00:38:15]. An example is the Bose-Einstein condensate of molecules in the ground state, which was achieved in November of the previous year [00:40:09]. This is considered a Nobel-level achievement [00:40:28].
Research with cold atoms and molecules also branches into attempts to measure dark matter [00:35:05]. For instance, accurate atomic clocks based on ultracold atoms have been proposed to detect certain types of dark matter, particularly if it has a structure of domains moving through the universe [00:35:35]. While dark matter’s gravitational interaction is known, its other interactions are still speculative [00:36:31].
Understanding the Universe’s Fundamental Nature
The study of cold atoms contributes to understanding concepts like time crystals [00:32:56] and the dual wave-particle nature of light [00:31:57]. Such research helps explore quantum physics at both extremely low and high temperatures, where classical mechanics breaks down [00:18:52]. Ultimately, this line of inquiry aims to answer fundamental questions about the nature of the universe [00:35:05].