From: mk_thisisit
Semiconductor spintronics is a branch of physics focused on utilizing the spin of electrons, in addition to their charge, for information processing and storage [01:19:19]. This field aims to overcome the limitations of current electronic architectures that primarily rely on electron charge [01:07:12].
The Birth and Evolution of Spintronics
The field of spintronics is considered to have roots in the work of Professor Tomasz Diem and David, who also formulated foundations of quantum mechanics for computer science applications [05:03:07]. The core idea, stemming from Professor Gałązka’s work in the last century, was to integrate magnetic ions into good semiconductors like gallium arsenide or silicon [05:25:27]. This combination allows for materials that possess both semiconductor properties (used in electronics) and magnetic properties (used for information recording) [06:18:22].
A significant breakthrough was demonstrating that applying voltage to a magnetic semiconductor can change its magnetic properties, thus opening possibilities for both recording and processing information [00:41:42] [07:02:04].
How Spintronics Utilizes Electron Spin
Electrons possess both a negative/positive charge and a property called spin [01:16:16]. Spin can be visualized as the electron rotating around its axis, producing a magnetic moment [01:52:03]. This magnetic moment can be used to record information, a principle already employed in magnetic memories and hard drives found in data centers [02:00:00] [02:34:34].
The ambition of spintronics extends beyond recording to actively using spins for processing information [02:54:15].
Spin for Information Processing
One approach involves placing an electron with its spin in a quantum dot [03:07:07]. When two such electrons in adjacent quantum dots interact, this interaction can be leveraged for information processing [03:30:00]. This forms the basis of a simplified quantum computer model [03:58:00].
The idea of using individual spins for information processing is about 30 years old [04:17:17]. Companies like Intel, in collaboration with Delft University of Technology, are working to scale this up to thousands of bits for quantum calculations [04:25:00].
Limitations of Current Electronics and the Need for New Architectures
Current electronics, based on transistors (like those in our phones), rely on the charge of electrons [01:04:04] [05:56:59]. While transistor density has increased exponentially (by 10 million times in recent decades), reaching billions of transistors per square centimeter [08:20:00], physical limits are being reached. Transistor sizes are now down to 5 nanometers, where distances between components are measured in atoms [09:13:00] [09:38:00]. This has led to a saturation in the speed of computers [09:44:00].
“Mura’s law says that the number of transistors doubles every year and a half… for 40 years or so this law worked but at the moment Mura’s law is actually getting a little saturated” [12:24:00]
This saturation necessitates a change in computer architecture, moving away from designs that have been in use for over 75 years [10:06:06]. One proposed change is to shift the information carrier, similar to how communication technologies moved from using electrons in wires to photons in optical fibers [14:09:00]. Spintronics proposes using electron spins as the new information carrier [15:01:01].
Spintronics for Memory
Spins can also be used in dynamic random-access memories (DRAM) and cache memories [15:21:00]. Current DRAMs require constant power to maintain information, leading to energy consumption and data loss upon power disconnection [15:38:00]. By utilizing magnetic materials based on spin, it’s possible to create faster, more energy-efficient cache memories that retain information without continuous power [16:03:00].
Quantum Computers and Spintronics
Quantum computers based on single spins in quantum dots are a promising avenue within spintronics [03:30:00]. However, quantum computing faces challenges, primarily decoherence, which refers to the loss of quantum properties due to interaction with the environment (e.g., thermal noise, electromagnetic signals) [22:16:00]. This interaction disturbs the quantum evolution of spins, making calculations prone to errors [24:25:00].
The Role of Topology
Topology, a branch of mathematics, is gaining importance in physics, particularly in the context of quantum computing [26:50:00]. If spins are arranged in a topologically non-trivial way, the resulting structure is more stable and less susceptible to disturbances like decoherence [27:08:00]. This means smaller memory units can be created that are more robust [27:22:00].
Combining materials with different topological indices can also lead to the creation of stable “edge states” that are insensitive to disturbances, making them ideal information carriers [28:01:01]. Microsoft, for example, is investing in the development of topological quantum computers that leverage these properties [28:34:00].
Metrology and Quantum Phenomena
Metrology, the science of measurement, is another area where quantum properties are crucial for achieving unprecedented precision [30:15:00]. Modern units of measurement, such as the second, are defined based on unchanging physical constants and atomic transitions (e.g., the cesium atom) [30:43:00]. This precision is vital for applications like GPS, which relies on extremely accurate atomic clocks on satellites [31:17:00].
Quantum phenomena like the Josephson effect (superconductivity) and the quantum Hall effect (occurring on the edge of 2D materials in strong magnetic fields) allow for translating microscopic quantum properties to macroscopic units, enabling highly precise definitions of units like the ampere and kilogram [32:33:00].
Research and Development in Europe
Europe has allocated significant funding, including a billion euros, for the development of quantum computing [20:51:00]. Poland, a beneficiary of European funds, is actively involved in this research, with laboratories dedicated to topological materials [35:12:00]. Despite strong scientific projects and increasing research grants, overall science funding in Poland remains below the global average [37:37:00]. The focus is on assessing scientific quality through grants obtained rather than other metrics [38:11:00].
Pioneering research, such as algorithmic chemistry that predicts chemical reactions, is being conducted [39:30:00]. This work has even touched upon fundamental questions like the origin of organic materials and life on Earth [40:07:00].
While there hasn’t been a scientific Nobel Prize from Poland in almost a century, Polish physicists like Professor Paczyński (astronomy) and Wojciech Żurek (decoherence and quantum computing) have been considered strong candidates [41:58:00]. The competition for scientific recognition, especially for awards like the Nobel Prize, is intense, with hundreds of proposals each year [42:26:00].