Physicists have created a theoretical "Quantum Rubik's Cube" where the colored squares exist in superimposed states. Unlike a classical Rubik's Cube, rotations can entangle the squares, making the puzzle significantly more complex. Researchers developed an algorithm to solve this quantum puzzle, focusing on maximizing the probability of reaching the solved state, rather than guaranteeing a solution in a specific number of moves. They discovered that counterintuitive moves, ones that seemingly scramble the cube, can actually increase the likelihood of ultimately solving it due to the nature of quantum superposition and entanglement.
William Bader's webpage showcases his extensive collection of twisty puzzles, particularly Rubik's Cubes and variations thereof. The site details numerous puzzles from his collection, often with accompanying images and descriptions of their mechanisms and solutions. He explores the history and mechanics of these puzzles, delving into group theory, algorithms like Thistlethwaite's and Kociemba's, and even the physics of cube rotations. The collection also includes other puzzles like the Pyraminx and Megaminx, as well as "magic" 8-balls. Bader's site acts as both a personal catalog and a rich resource for puzzle enthusiasts.
HN users generally enjoyed the interactive explanations of Rubik's Cube solutions, praising the clear visualizations and step-by-step approach. Some found the beginner method easier to grasp than Fridrich (CFOP), appreciating its focus on intuitive understanding over speed. A few commenters shared their personal experiences learning and teaching cube solving, with one suggesting the site could be improved by allowing users to manipulate the cube directly. Others discussed the mathematics behind the puzzle, touching on group theory and God's number. There was also a brief tangent about other twisty puzzles and the general appeal of such challenges.
Summary of Comments ( 2 )
https://news.ycombinator.com/item?id=43746868
HN commenters were generally skeptical of the article's framing. Several pointed out that the "quantum Rubik's cube" isn't a physical object, but a theoretical model using quantum states analogous to a Rubik's cube. They questioned the practicality and relevance of the research, with some suggesting it was a "solution in search of a problem." Others debated the meaning of "optimal solution" in a quantum context, where superposition allows for multiple states to exist simultaneously. Some commenters did express interest in the underlying mathematics and its potential applications, although these comments were less prevalent than the skeptical ones. A few pointed out that the research is primarily theoretical and explorations into potential applications are likely years away.
The Hacker News post titled "Physicists Designed a Quantum Rubik's Cube and Found the Best Way to Solve It" generated several comments, many of which delve into the nuances of the research and its implications.
Several commenters discussed the nature of the "quantum Rubik's cube" itself. Some pointed out that it wasn't a physical object but rather a theoretical model represented by a quantum system. This led to discussions about the differences between manipulating a physical Rubik's cube and manipulating a quantum state. One commenter specifically highlighted the distinction between physical rotations and unitary transformations applied to the quantum system.
The concept of "solving" the quantum Rubik's cube also sparked debate. Commenters clarified that the research wasn't about finding a sequence of moves like in a classical Rubik's cube, but rather about finding the optimal quantum gate sequence to transform a given quantum state into a target state. This involved discussions about quantum gates, unitary transformations, and the complexity of these operations.
The topic of optimization was also prominent. Commenters explained that the researchers used a specific optimization algorithm (GRAPE) to find the most efficient way to perform the state transformation. This led to discussions about the computational cost of these calculations and the potential applications of such optimization techniques in other quantum computing problems.
Some comments focused on the practical implications of this research. While acknowledging the theoretical nature of the work, some commenters speculated about potential applications in quantum information processing and quantum control. Others questioned the immediate practical relevance, emphasizing that this was fundamental research.
One commenter expressed skepticism about the novelty of the research, suggesting that the problem being addressed was already well-known in quantum control theory. This prompted counter-arguments from other commenters who defended the value of the research, emphasizing the specific contributions made by the authors.
Finally, some comments addressed the accessibility of the original article and the ScienceAlert summary. Some appreciated the simplified explanation provided by ScienceAlert, while others expressed a desire to delve into the more technical details presented in the original research paper.