From: mk_thisisit
Polish physicist Michał Parniak has achieved states in quantum physics that were previously unmanaged globally [00:00:00]. His work includes the creation of a record-breaking quantum memory [00:00:55].
Development of Quantum Memory
The development of this memory began around 2011 [00:01:08]. At the time, a similar memory was being created in China [00:00:09], but when the Polish team published their results, it was discovered their memory was three times more capacious [00:00:11], a record they largely still hold [00:02:20].
Functionality of the Quantum Memory
This quantum memory operates by preparing a cloud of atoms in a vacuum [00:01:33]. These atoms are capable of absorbing very weak, quantum single photons [00:01:37]. The memory can:
- Remember a large number of photons simultaneously [00:00:14].
- Store them for a period [00:00:17].
- Potentially process them by performing specific quantum operations [00:00:21].
It functions as a specialized quantum processor capable of performing particular operations on light, which are valuable in fields like quantum metrology and quantum communication [00:02:00].
The memory stores information about light within the state of its atoms, particularly their spins [00:05:17].
Applications and Further Research
Quantum Metrology and Communication
The record-breaking capacity of this memory is utilized for further experiments [00:02:25], particularly in quantum metrology and quantum communication [00:02:11].
Macroscopic Entanglement
The memory’s ability to store many photons allowed for the creation of macroscopic entangled states [00:03:31]. While the team also explored macroscopic entanglement in Copenhagen involving a mechanical membrane entangled with atomic spins [00:03:07], their memory enabled showing entanglement between many photons and photons still stored within the memory [00:03:41]. This achieved entanglement with a particularly large “object” – a record in terms of scale [00:03:54]. The entanglement is considered “hybrid” because it combines incompatible systems, such as cesium atom spins and a mechanical oscillator [00:04:26].
Spectral Analysis and Chemical Research
More recently, the memory has been enhanced to process information, acting as a specific quantum processor [00:06:05]. Its task is to extract spectral information from photons, determining their precise spectral lines [00:06:41]. These spectral lines serve as “imprints” of molecules, for instance, from an atmosphere [00:06:56]. This allows for precise distinction of very close spectral lines [00:07:06], potentially useful for understanding the composition of celestial bodies like clouds on Venus [00:05:40].
Understanding the Quantum-Classical Boundary
The research aims to understand the differences between the classical and quantum worlds by creating quantum states of increasingly macroscopic objects [00:07:12]. The question is where the boundary lies between the non-intuitive, probabilistic quantum world (described by the Schrödinger equation) and the deterministic classical world (described by Newton’s laws) [00:08:03].
The Schrödinger's Cat Analogy
This problem is exemplified by Schrödinger’s cat thought experiment: If a cat in a box is isolated and its life/death linked to a quantum atom in superposition, where does the quantum description of the atom transition to a classical description of the cat? [00:10:11] Researchers are trying to understand the mechanisms involved in this transition, examining the quantum basis of detectors that connect microscopic quantum events to macroscopic outcomes [0:10:48].
Quantum States of Mechanical Objects
Experiments at the Niels Bohr Institute in Copenhagen involved introducing a small mechanical membrane, similar to a drum’s tension (nanometers thick, millimeters wide), into a quantum state [00:11:46]. They managed to interact with individual photons and control this interaction [00:12:33]. They introduced certain superposition states [00:12:57] and, importantly, achieved the ground state of this mechanical oscillator through laser cooling [00:13:15]. Even at absolute zero, the ground state exhibits quantum fluctuations, which are observable for this macroscopic object, demonstrating the fundamental limits of precision in measuring its position [00:13:45].
Quantum Gravity and Superposition
The ultimate goal of this research is to find the bridge, or the interface, between the quantum and classical worlds [00:10:02]. This includes quantum theory of gravity [00:14:08]. Experiments are underway in Austria to place mechanical oscillators (small balls) in a state of superposition, being in two places at once [00:14:37]. Such an object in superposition would have its own gravity, offering a potential path to observe quantum gravity [00:15:01]. This requires both placing increasingly macroscopic objects into quantum states and increasing the precision of gravity measurements [00:15:24].
Limits of Quantum Measurement and Metrology
Quantum metrology is a practical field focused on building systems that measure with enhanced precision by using quantum mechanics to reduce “quantum noise” [00:15:58]. This technique, called “squeezing,” reduces fluctuations in light in one aspect at the cost of increasing them where they are irrelevant [00:16:29].
Practical applications of quantum metrology are already in use:
- Gravitational Wave Detectors: Operating detectors in the US, Italy, and Japan use quantum light engineering to nearly double the precision of gravitational wave measurements [00:16:51]. This involves precisely measuring the position of mirrors, a challenge due to light’s quantum fluctuations and photon pressure [00:17:26].
- General Measurement Limits: All measurements have their quantum limits, which are determined by the fluctuations of the measurement tool and the object being measured [00:18:23].
Information from Light and its Spectrum
The light spectrum carries information with two main applications:
- Chemical Research: Studying the composition of molecules [00:18:56].
- Information Encoding and Decoding: More efficiently “packing” light’s degrees of freedom to encode and decode information, which is crucial for telecommunications [00:19:06]. For example, better encoding could significantly increase transmission capacity in optical fibers, especially expensive transatlantic cables [00:19:47].
Encoding Information in Photons
Photons are considered excellent “workhorses” for quantum information due to the ability to control them well [00:21:21]. While the limits of encoding information in matter are vast but currently inaccessible [00:22:43], information can be recorded in photons via:
- Polarization: Associated with the photon’s spin [00:23:09].
- Temporal Degree of Freedom: For example, sending two pulses of light containing a single photon, where the photon is in a superposition of being in either pulse [00:23:22].
Researchers are also exploring the use of microwave photons for quantum information [00:21:12].
Super-Resolution and Astronomical Imaging
Experiments focus on developing more universal devices for super-resolution spectral studies, extending their capabilities from infrared to other wavelengths of light [00:23:51].
This technology has implications for astronomical imaging, similar to how the Event Horizon Telescope constructs images of black holes from microwave detectors across Earth [00:24:23]. The goal is to use quantum devices to perform more precise microwave measurements or obtain new information, potentially leading to more accurate images of black hole event horizons [00:25:29]. Placing such detectors in space could further increase the “lens” size to that of the entire solar system [00:26:07].
Beyond black holes, enhanced microwave measurements could reveal more about space structures, notably the cosmic microwave background (CMB) radiation [00:26:16]. This radiation, a remnant of the Big Bang, has fluctuations from which many features of the universe can be predicted [00:26:23].
The motivation for this research is dual: to advance the understanding of the universe and to improve practical applications like communication networks (5G, 6G) [00:27:17].