From: mk_thisisit
Introduction to Spintronics
Spintronics is a branch of physics focused on utilizing the spin of electrons, in addition to their charge, for information processing and storage [01:16:16]. While traditional electronics primarily use the negative or positive charge of an electron for power [01:12:12], electrons also possess a property called “spin” (or “kręt” in Polish), which results from their rotational motion similar to Earth rotating on its axis [01:50:20]. This spin produces a magnetic moment that can be used to record information [02:00:00].
Information Storage with Spin
Magnetic memories utilize materials where more electrons align with one spin direction compared to the opposite, creating magnetism from unpaired magnetic moments [02:08:08]. This principle has been used for many years, as exemplified by Franz Joseph’s voice recorded on a magnetic disc [02:22:00]. Modern hard drives in data centers achieve huge recording densities, with billions of transistors on one square centimeter [00:20:20], enabling services like Google or movie streaming [02:43:00].
Information Processing with Spin
The ambition in spintronics extends beyond recording to processing information using electron spins [02:54:00]. A key concept involves using electrons in quantum dots (which were the subject of a Nobel Prize in chemistry [03:11:00]). By controlling the number of electrons in these dots, even down to a single electron, and observing their interaction, information processing can occur [03:22:00]. This interaction, if isolated from the environment, adheres to the laws of quantum mechanics, forming a simple model of a quantum computer [03:52:00]. The idea of using individual spins for information processing is about 30 years old [04:17:00], with companies like Intel collaborating with Delft University of Technology to scale up quantum calculations to thousands of bits [04:25:00].
Origins of Spintronics
The foundational work for spintronics is attributed to Daniel Los and David who formulated the principles of quantum mechanics for computer science applications [05:00:00]. Professor Gałązka introduced the idea of combining semiconductors (like silicon) with magnetic materials (like iron) by introducing magnetic ions into semiconductors such as gallium arsenide or cadmium telluride [05:24:00]. This allows for materials with both semiconductor and magnetic properties [06:06:00]. A significant discovery showed that applying voltage to these magnetic semiconductors can change their magnetic properties, which are used for information recording and processing [07:02:00].
Limitations of Classical Electronics
Modern electronics relies on transistors, with billions packed onto a square centimeter [00:20:20]. This miniaturization has been a driving force for progress, increasing transistor count by 10 million times in recent decades [08:20:00] and reducing their price to 100 times less than printing a single letter in a book [01:36:00]. Current transistors are as small as 5 nanometers, where a human hair is 10,000 times larger [09:13:00]. However, this miniaturization is reaching physical limits, and the speed of computers, which once grew rapidly from megahertz to gigahertz, has slowed [09:40:00].
Moore’s Law, which states that the number of transistors on a chip doubles approximately every 18 months [01:24:00], is becoming saturated due to these physical limits [01:42:00]. This saturation means new architectures are needed, moving beyond the 75-year-old architecture developed during wartime [10:06:00].
New Information Carriers and Technologies
The current challenge is to find new information carriers beyond the electron’s charge [01:14:12], similar to how data transfer evolved from electrons in wires to photons in optical fibers [14:12:00]. Spintronics proposes using spins for information processing [15:01:00].
Spintronics in Dynamic Memories
Spins could revolutionize dynamic random-access memory (DRAM) and cache memories [15:21:00]. Current charge-based dynamic memories require constant refreshing and lose information when power is disconnected, consuming significant energy [15:31:00]. Utilizing magnetic materials from disk memory for fast cache memory could reduce energy consumption by permanently storing information with spins [16:03:00].
Antiferromagnetics
Antiferromagnetic materials, where neighboring spins compensate each other resulting in no external magnetic field [17:05:00], offer advantages for memory. Because these spins do not interact with neighbors, they can be brought closer together without interference (crosstalk), allowing for even smaller memory units [17:48:00].
Quantum Computing Competition
The future of information processing is highly competitive, with various approaches to building quantum computers including those based on quantum dots, superconductivity, trapped ions, or neutral atoms [18:32:00]. Europe has allocated a billion euros for the development of quantum computing [20:51:00], and a decision on a 15 million euro quantum computer purchase for a center in Poznań is pending [18:51:00]. Currently, superconductors are considered the most advanced, but challenges remain in scaling them up due to nonlocality and crosstalk issues in quantum mechanics [19:54:00]. Quantum dots might prove better in controlling individual elements without disturbing the rest of the system [20:36:00].
Challenges: Decoherence and Noise
A significant limitation in quantum evolution is electromagnetic noise [21:38:00]. The transition from the quantum world to the classical world is limited by “decoherence,” a term coined by Polish physicist Wojciech Żurek [22:12:00]. Żurek observed that interaction with the environment, such as thermal noise from neighboring atoms or electromagnetic signals, disrupts quantum evolution [22:56:00]. Quantum phenomena like diffraction and interference, which are characteristic of electron waves, disappear when noise causes slight changes in wavelength [23:21:00]. This interaction with the environment and the nonlocality of quantum mechanics are the primary difficulties in building large quantum computers [24:13:00].
Topology in Quantum Physics
Topology is a branch of mathematics concerned with properties that remain invariant under continuous deformation. In physics, it describes properties that differentiate materials based on characteristics like the arrangement of atoms in lattices [25:16:00]. For example, a hoop can have different “topological classes” depending on how many times it is twisted, and transitioning between these classes requires tearing the material [25:46:00]. This is distinct from geometry, which focuses on shapes like cubes or spheres [26:26:00].
In spintronics, if spins are arranged in a non-zero topological index, the structure becomes more stable and less susceptible to disturbances [27:08:00]. This allows for even smaller, more robust memory units [27:22:00]. When materials with different topological indices are combined, stable “edge states” are created at their boundary [28:01:00]. These edge states are highly stable and insensitive to disturbances, making them ideal information carriers [28:18:00]. Microsoft is actively developing topological quantum computers which leverage this property to reduce the impact of decoherence [28:32:00].
Metrology and Quantum Phenomena
Metrology, the science of measurement, deals with establishing precise units and standards. The introduction of standardization in the 19th century had a huge impact on the industrial revolution [29:13:00]. Initially, standards like the meter and kilogram were physical artifacts [30:00:00]. However, it was later discovered that the world could be described more precisely using fundamental physical constants, which have maintained their values over billions of years [30:15:00].
Today, units are defined based on these constants. For example, the unit of time (second) is based on the frequency of light emitted during intra-atomic transitions in a cesium atom, measured with very high accuracy using atomic clocks [30:43:00]. This precision is crucial for technologies like GPS, which relies on four atomic clocks on satellites and relativistic corrections to determine position with meter accuracy [31:17:00].
Quantum phenomena like the Josephson effect (which gives voltage) and the quantum Hall effect (occurring at the edge of two-dimensional materials in strong magnetic fields) allow for the precise expression of macroscopic units like the kilogram and ampere based on microscopic constants such as the electron charge and Planck’s constant [32:10:00]. This translation from the microscopic to the macroscopic world creates units more precise than any previously existing [33:55:00], opening new possibilities for applications [34:32:00].
Progress and Funding in Polish Science
Poland has made significant progress in scientific research, benefiting from large subsidies from the European Union, specifically the European Intelligent Development fund [35:07:00]. Research projects are often of very high quality, and Polish scientists are contributing to global advancements, particularly in areas like information and communication technologies using quantum computing [36:06:00]. The number of European Research Council grants received by Polish institutions is also growing [37:16:00].
However, the overall financing of science in Poland remains low compared to the global average, which is around 3% of GDP, while Poland struggles to reach 2% [37:37:00]. To improve, it is suggested that scientific units and scientists should be assessed based on the number of grants obtained through expert peer review, rather than other metrics, to ensure quality and encourage groundbreaking research [38:09:00].
Examples of Groundbreaking Research
An example of groundbreaking research in Poland is the work of Professor Bartosz Grzybowski, who developed an algorithmic approach to chemistry. His programs predict chemical reactions, leading to insights into how the first organic materials might have formed on Earth [39:35:00].
Nobel Prizes in Science
Despite significant scientific contributions, Poland has not received a Nobel Prize in physics or chemistry for almost a century [40:47:00]. While Poland has received Nobel Prizes in poetry [41:11:00], scientific recognition has been elusive. Notable Polish scientists who were considered strong candidates include:
- Professor Paczyński, an astronomer recognized for his research on microlensing [42:01:00].
- Wojciech Żurek, whose school of thought in quantum computing is highly regarded, particularly for his work on decoherence [42:47:00].
- Iono and Dawid Shalom, who were not nominated for the Nobel Prize despite receiving the European Physical Society award, which often precedes the Nobel [00:00:00], [43:27:00]. The Nobel committee receives hundreds of nominations each year, making selection highly competitive and sometimes unexpected [42:26:00].