From: mk_thisisit
Polish physicist Michał Parniak has achieved states in quantum physics previously unmanaged, including the creation of a record-breaking quantum memory [00:00:00]. This memory can store many photons simultaneously, hold them, and even perform quantum operations [00:00:14].
Quantum Memory as a Processor
The quantum memory, developed starting around 2011, is a cloud of atoms in a vacuum capable of absorbing light, specifically weak, single photons [01:08:00]. It is capable of remembering and storing numerous photons at once, and potentially processing them by performing specific quantum operations [01:48:00]. This makes it a type of quantum processor designed for specific tasks on light, useful in fields like quantum metrology and quantum communication [02:00:00]. The memory achieved record-breaking capacity, capable of storing the most photons, a record still largely held [02:17:00].
More recently, this memory has been advanced to not just store and reproduce photons, but to process the information within [06:05:00]. Its specific task is to extract spectral information from photons, determining the precise spectral lines they consist of [06:32:00]. These spectral lines serve as “imprints” of molecules, for instance, from an atmosphere [06:56:00]. This enables the device to very precisely distinguish between closely spaced spectral lines [07:06:00].
Quantum Metrology and Measurement Limits
Quantum measurements constitute a highly practical field known as metrology [15:54:00]. It is considered one of the most promising areas, potentially even more so than quantum computers [16:04:00]. Quantum metrology involves constructing systems for measurement and using quantum mechanics principles to minimize quantum noise, thereby improving measurement precision [16:13:00]. This technique is often referred to as “squeezing,” which involves reducing light fluctuations by allowing them to increase where they are less critical [16:29:00].
Experiments in quantum metrology are already being applied in practical measurements [16:42:00].
Gravitational Wave Detectors
Gravitational wave detectors operating in the United States, Italy, and Japan utilize quantum light engineering [16:51:00]. This technology, developed by quantum physicists, has approximately doubled the precision of gravitational wave measurements [17:00:00].
Position Measurement
Quantum metrology is also useful for measuring position, such as the position of mirrors [17:24:00]. Challenges arise because light itself has quantum fluctuations [17:34:00]. Increasing the amount of light makes it more classical, but also risks disturbing the mirrors due to photon pressure [17:42:00]. There is an optimum balance, and quantum mechanics tricks can improve this optimum [18:12:00]. All measurements face their own quantum limits, which are determined by the fluctuations of both the measuring tool and the object being measured [18:23:00].
Information Encoding and Decoding
The light spectrum offers two main applications: chemical research and studying molecular composition [18:52:00]. Another significant application is the potential to better “pack” the degree of freedom of light to encode and decode information [19:06:00]. Better utilization of spectral degrees of freedom is crucial for telecommunications, especially for long-distance optical fibers like those under the Atlantic, where increasing transmission by a factor of 10 would be immensely valuable [19:25:00].
Researchers are working to invent protocols for better decoding information [20:20:00]. While we understand how to use photons’ features to encode information, the question of how to encode it more densely is an interesting field [21:02:00]. The use of microwave photons for this purpose is also being explored [21:12:00]. Photons are considered excellent “workhorses” for quantum information due to the ability to control them well and conduct experiments that push the boundaries of understanding how quantum information operates [21:21:00]. Understanding the structure of quantum information brings us closer to comprehending how quanta work [21:52:00].
Current limits of information encoding with photons in visible light include using the light’s polarization (associated with the photon’s spin) or its temporal degree of freedom [23:03:00]. For example, a single photon in a state of superposition can exist in either of two light pulses [23:25:00].
Super-resolution and Astronomical Imaging
These studies aim to create devices with even greater “super-resolution” [23:42:00]. Experiments are extending the application of these protocols from infrared light to other wavelengths, working towards a more universal device [24:02:00].
In astronomy, the famous image of a black hole, for instance, is not a single photo but a visualization created from many superimposed images collected by microwave detectors across the Earth [24:23:00]. To image such small objects, a huge telescope is needed, effectively using the entire Earth as a lens, though with limited “pixels” or coverage [24:34:00]. The same principles can be applied in the optical domain [25:18:00]. Research is ongoing to use devices that work with atoms and microwave light to perform more precise microwave measurements or gain new information from single photons [25:29:00]. This could potentially lead to a more accurate image of a black hole’s event horizon using microwaves [25:46:00]. Placing such detectors in space could further increase the “lens” size to that of the entire solar system [26:07:00].
Beyond black holes, microwaves can also provide information about the cosmic microwave background radiation [26:16:00]. This radiation, a remnant of the Big Bang, contains fluctuations from which many features of the universe can be predicted [26:23:00]. It is not generated by celestial bodies but is omnipresent [26:45:00]. While not exclusively quantum physics, the goal is to measure these microwaves more precisely, motivated by the desire to understand the universe and improve communication technologies like 5G and 6G [27:02:00].