From: mk_thisisit
Polish physicist Michał Parniak has achieved states in quantum physics that are considered record-breaking, including states of macroscopic entanglement [00:00:00]. This research explores the boundaries between the quantum and classical worlds [07:17:19].
Quantum Memory: A Foundational Achievement
Parniak’s team developed a record-breaking quantum memory capable of storing a large number of photons simultaneously [00:14:00]. This memory, first developed around 2011, proved to be three times more capacious than a similar one being created in China at the same time [01:08:00], [01:11:00], [01:26:00].
This memory prepares a cloud of atoms in a vacuum, allowing them to absorb weak, single photons [01:33:00], [01:43:00]. It can store many photons, process them, and perform specific quantum operations [01:48:00], [01:57:00]. This capability makes it a specialized quantum processor, useful in areas like quantum metrology and quantum communication [02:00:00], [02:11:00]. The record-breaking capacity is continually utilized for further experiments [02:25:00], [02:29:00].
Achieving Macroscopic Entanglement
Michał Parniak’s work has led to the achievement of macroscopic entanglement [02:54:00]. This was explored in two ways:
- Copenhagen Experiment In Copenhagen, an experiment entangled a mechanical membrane (a drum-like object) with the spins of atoms [03:07:00], [03:15:00]. This was a “hybrid” entanglement, combining systems like cesium atom spins and a mechanical oscillator that are typically incompatible [04:26:00], [04:32:00]. The objects involved were exceptionally large, both in the number of atoms and the size of the mechanical membrane [04:14:00].
- Warsaw Experiment with Quantum Memory In Warsaw, using the record-breaking quantum memory, the team managed to entangle many photons that were still stored within the memory [03:31:00], [03:41:00], [03:52:00]. This was a record for achieving entanglement with such a large number of photons [03:58:00].
The ability to store and process light within the quantum memory also allows for the extraction of spectral information from photons [06:07:00], [06:17:00]. This involves distinguishing very precise spectral lines, which are essentially “imprints of molecules” (e.g., from an atmosphere) [06:41:00], [06:56:00]. This capability has applications in chemical research and studying molecular composition [18:56:00].
Understanding the Quantum-Classical Boundary
Parniak’s research aims to understand the differences between the classical world and the quantum world, particularly the boundary where objects transition from behaving non-intuitively according to quantum laws to behaving deterministically according to classical physics [07:17:19], [08:05:00]. Experiments involve creating quantum states of objects that are increasingly macroscopic [09:34:00].
Schrödinger’s Cat Analogy
The famous thought experiment of Schrödinger’s cat illustrates this boundary [10:11:00]. If an atom in a quantum superposition state is linked to the cat’s life or death, the question arises: where does the atom’s quantum description stop, and the cat’s classical state begin [10:19:00], [10:40:00]? Experimental studies like Parniak’s try to examine the “mechanism” between the quantum object and the classical detector [10:48:00], [10:51:00].
For instance, at the Niels Bohr Institute in Copenhagen, a small membrane (similar to a drum’s tension, nanometers thick, but millimeters wide) was introduced into a quantum state [11:46:00], [11:53:00]. Its vibration aspect was brought to a quantum state, and interaction with individual photons was controlled [12:24:00], [12:35:00]. Although not a full “Schrödinger’s cat,” certain superposition states near the quantum state were achieved for this membrane [12:57:00].
Ground State and Quantum Fluctuations
A key challenge in these studies is reaching the ground state of a mechanical oscillator [13:08:00]. At absolute zero temperature (achieved via laser cooling), a mechanical oscillator still exhibits quantum fluctuations [13:19:00], [13:39:00]. These fluctuations are observable for macroscopic objects and indicate that even at absolute zero, an object retains some movement, limiting the infinite precision of position measurement [13:45:00], [13:54:00].
Quantum Gravity and Macroscopic Superposition
A potential bridge to understanding the quantum-classical divide is the quantum theory of gravity [14:08:00]. Experiments are being conducted (e.g., in Austria) to introduce macroscopic objects, like small balls, into a state of superposition (being in two places at once) [14:33:00], [14:41:00], [14:48:00].
The motivation for this is that an object in such a quantum superposition of positions would have its own gravity [14:55:00], [15:01:00]. The hope is to eventually observe gravity from an object that is in quantum superposition, bridging the gap between increasing the macroscopic nature of quantum states and enhancing the precision of gravity measurements [15:40:00], [15:46:00].