What the Hell Is Quantum Chess? | IE – Interesting Engineering
Have you ever heard of Quantum Chess? If not, we are confident you are in for a real treat.
Read on to find out more about this interesting take on a very ancient strategy game. But brace yourself, things are about to get a little "spooky".
RELATED: WINNER OF THE WORLD'S FIRST QUANTUM CHESS TOURNAMENT ANNOUNCED
Quantum Chess is a variant of the classical strategy game. It incorporates the principles of quantum physics. For example, unlike traditional chess, the piecescan be placed into a superposition of two locations, meaning that a piece can occupy more than one square.
Unlike chesspieces in the conventional game where, for example, a pawn is always a pawn, aquantum chesspiece is a superposition of "states", with each state representing a different conventional piece.
Conventional chess is a very complex game, although it is possible for computer algorithmsto beat the world's greatest chess playersby accurately determining the moves necessary to win the game at any point.
The main rationale behind the creation of Quantum Chess is to introduce an element of unpredictability into the game, and thereby place the computer and the human on a more equal footing. The game can also help "level the playing field" somewhat between human players of widely different skills and experience with chess.
Its like youre playing in a multiverse but the different boards [in different universes] are connected to each other, said Caltech physicist Spiros Michalakis during aLivestreamof a recent Quantum Chess tournament. It makes 3D chess fromStar Treklook silly.
But don't let the term intimidate you. New players to the game don't need to be experts in quantum physics a basic understanding of chess is more important actually.
While it might sound like something of a gimmick, Quantum Chess is an interesting and entertaining spin on the classic game that many find enjoyable. Unless, of course, you cannot live without knowing for sure what and where each piece is at any given time.
If that is the case, you might find this one of the most frustrating games ever created!
Quantum Chess, as you have probably already worked out, is not like any game of classical chess you have ever played. But, it is important to note that there are also several variants of Quantum Chess.
The best known is probably the one created by Chris Cantwell when he was a graduate student at theUniversity of Southern California.This variant differs from other examples by the fact that it is more "truly quantum" than others.
My initial goal was to create a version of quantum chess that was truly quantum in nature, so you get to play with the phenomenon,Cantwell said in an interview with Gizmodoback in 2016.
I didnt want it to just be a game that taught people, quantum mechanics. The idea is that by playing the game, a player will slowly develop an intuitive sense of the rules governing the quantum realm. In fact, I feel like Ive come to more intuitively understand quantum phenomena myself, just by making the game, he added.
In Cantwell's version of Quantum Chess, this superposition of pieces is indicated by a ring that details the probability that the piece can actually be found in a given square. Not only that, but when moving a piece, each action can also be governed by probability.
You can think of the pieces of the game existing on multiple boards in which their numbers are also not fixed. The board you see is a kind of overview of all of these other boards and a single move acts on other boards at the same time.
Whenever a piece moves, many calculations are made behind the scenes to determine the actual outcome, which could be completely unexpected.
That being said, moves do follow the basic rules of traditional chess, including things like castling and en passant. However, there are a few important differences:
Pieces in this version of Quantum Chess can make a series of either "quantum moves" (except for pawns) or regular chess moves. In this sense, the pieces can occupy more than one square on the multiverse of boards simultaneously.
These moves also come in a variety of "flavors".
The first is a move called a "split move". This can be performed by all non-pawn pieces and allows a piece to actually occupy two different target squares that it could traditionally reach in normal chess.
But, this can only be done if the target square is unoccupied or is occupied by pieces of the same color and type. A white knight, for example, could use this kind of move to occupy the space of another white knight.
Such a move cannot; however, be used to capture an opponent's piece.
Another interesting move is called a "merge move". This can be performed by all pieces except pawns and, like a split move, can only be performed on an unoccupied square or one occupied by a piece of the same type and color.
Using our previous example of a white knight, this would mean that two white knights could merge together on the same square. Again, this move cannot be used to capture enemy pieces.
So how do you take pieces in Quantum Chess?
Well, when two pieces of different colors meet on the same square the game makes a series of measurements.These measurements are designed to answer a specific yes or no question.
For example, the game's mechanics will look at certain squares to determine if they are occupied or not.The outcome of this can be to cause a piece's "superposition" state to "collapse".
If the superposition state collapses, then the desired move will be performed. If not, the move is not made and the player's turn ends.
Capturing is also very different in a game of Quantum Chess. When a player attempts to do this, the game will make calculations for the square where the piece is situated and for its target square, as well as any other squares in its path, to answer the question, "is the attacking piece present and can it reach the target?".
If the answer is no, it is important to note that this doesn't necessarily mean the attacking piece is not present. Nor does it mean that its path is blocked.
Another interesting concept of Quantum Chess is called "exclusion". If a moving target is occupied and is in superposition by a piece that cannot be captured by the move, it is called an exclusion move.
Again, calculations are made for the target square and any squares in the path of an allowed move by a piece in superposition. This is done to answer the same question as capturing, with similar outcomes.
Castling is also very different in Quantum Chess. This move always involves two targets, and the same measurements are made for both targets. Castling cannot be used to capture, and will always be an exclusion move.
So, you might be wondering how you actually win a game of Quantum Chess?
Just like traditional chess, the aim of the game is to capture the opponent's king. However, unlike in traditional chess, the concept of checkmate does not exist.
To win, the enemy king must no longer actually exist on the board. As any piece, including the king, exist in a state of superposition, they can either be captured or not which further complicates the issue.
The game, therefore, continues until it is known, with certainty, that a particular player has no king left. For this reason, it is possible for both players to lose their king at the same time and the game would then be considered a draw.
Another important thing to note is that each player has a set amount of time for the game. For this reason, you can also win by running an opponent's time out.
How you play Quantum Chess depends on the variant of the game you are playing. We have already covered the rules of one variant above, and that game can be played throughQuantum Realm Games. But another version created byAlice Wismath at theSchool of Computing at Queen's University in Californiahas some slightly different rules.
You can try that game for yourself here.
In her version, each player has sixteen pieces. These pieces are in a quantum state of superposition of two types: a primary and a secondary type.
They are also in an unknown (quantum) type or a known (classical) type.When a piece is "touched" it collapses into its classical state and has an equal probability of becoming either a primary or secondary type. The king, however, is an exception, and is always in a classical state.
Each player has one king and its position is always known.
All other pieces are assigned the following primary piece types: left rook, left bishop, left knight, queen, right knight, right bishop, right rook, and pawns one through eight. Secondary piece types are then randomly assigned from this same list of piece types so that each type occurs exactly twice in the player's pieces.
Each piece is created at the start of each game and superpositions are not changed throughout the game. Pieces also start as they would in regular chess, on the first two rows, according to their primary piece type with all, except the king, in a state of superposition.
Once a quantum state piece is touched (i.e. chosen to move), it collapses into one of its two predetermined states, and this state is suddenly revealed to both players.
This can mean that a pawn in the front row can suddenly become a white knight once the piece has been "touched". You won't know until the piece's quantum state collapses.
Quantum Chess boards are the same as regular chess boards except that when a piece lands on a white square it remains in its classical state. When pieces land on black squares, however, they undergo a quantum transformation and regain, if lost, their quantum superposition.
This means that a previously "revealed" pawn can also suddenly transform into a queen if that was one of its predetermined primary or secondary types. A very interesting concept indeed.
To play the game, each player chooses a piece to move and must move it. If the quantum piece collapses into a piece type with no possible moves, then the player's move is over.
Pieces in classical states with no possible moves cannot be chosen. All pieces move as they would in classical chess with some of the following exceptions:
Pieces can also be captured as normal, and quantum pieces collapse from their superposition state and are removed from play.
If a player touches a quantum piece that collapses into a state that puts the opponent's king in check, their move is over. The opponent, however, is not required to get out of check in such circumstances.
Pawns that reach the opposite side of the board can be promoted to aqueen, bishop, rook, or knight, regardless of the number of pieces of that type already in the game. Also, if a piece in the quantum state on the far row is touched and revealed to be a pawn, it is promoted, but the promotion takes up the turn. The superimposed piece type is not affected.
To win the game, each player must capture the enemy's king, as a checkmate does not happen in Quantum Chess. For this reason, kings can actually move into a position that would normally be considered check.
Games are considered a draw if both opponents are left with only their king in play or 100 consecutive moves have been made with no captures or pawn movements by either player.
It was recently announced that the world's first Quantum Chess tournament had been won by Aleksander Kubica, a postdoctoral fellow at Canada's Perimeter Institute for Theoretical Physics and Institute for Quantum Computing. The tournament was held on the 9th of December 2020 at the Q2B 2020 conference.
The tournament games are timed, and Kubica managed to beat his opponent, Google's Doug Strain, by letting him run out of time. This currently makes Kubica officially the best Quantum Chess player in the world.
Not a bad way to see out one of the worst years in living memory.
And that, ladies and gentlemen, is a wrap.
If you like the sound of playing Quantum Chess, why not check out either of the versions we have discussed above in this article. Who knows, you might get proficient enough to challenge Kubica for the title in the not too distant future?
Read this article:
What the Hell Is Quantum Chess? | IE - Interesting Engineering
- Building the world's first open-source quantum computer - Phys.org - January 22nd, 2026 [January 22nd, 2026]
- Rigetti: Not The Quantum Computing Stock To Own - There Are Better Alternatives - Seeking Alpha - January 22nd, 2026 [January 22nd, 2026]
- IQM and Bechtle to install five-qubit quantum computer at Heilbronn University, Germany - BeBeez International - January 22nd, 2026 [January 22nd, 2026]
- Exclusive from 36Kr: Team with Tsinghua and Harvard Backgrounds Developing Quantum Computers, Revenues Double, Secures Hundreds of Millions in... - January 22nd, 2026 [January 22nd, 2026]
- Quantum error correction with logical qubits - EurekAlert! - January 22nd, 2026 [January 22nd, 2026]
- These 3 Giant Tech Stocks Are Poised for Explosive Quantum Growth - The Motley Fool - January 22nd, 2026 [January 22nd, 2026]
- The quantum-cryptography cliff: From roadmaps to reality - SC Media - January 22nd, 2026 [January 22nd, 2026]
- MIT Researchers Demonstrate Faster Cooling Method for Chip-Based Trapped-Ion Quantum Systems - The Quantum Insider - January 22nd, 2026 [January 22nd, 2026]
- It started with a cat: How 100 years of quantum weirdness powers todays tech - Texas A&M Stories - January 22nd, 2026 [January 22nd, 2026]
- The Smartest Quantum Computing Stock to Buy for 2026 - The Motley Fool - January 22nd, 2026 [January 22nd, 2026]
- Network-based Quantum Computing Achieves Distributed Fault-Tolerance with Many Small Nodes - Quantum Zeitgeist - January 22nd, 2026 [January 22nd, 2026]
- RGTI and QUBT: This Analyst Sees the Next Jump in Quantum Stocks - Yahoo Finance - January 22nd, 2026 [January 22nd, 2026]
- Building the worlds first open-source quantum computer - University of Waterloo - January 20th, 2026 [January 20th, 2026]
- The 3 Best Quantum Computing Stocks to Buy for 2026 - Yahoo Finance - January 14th, 2026 [January 14th, 2026]
- Safeguard Your WAN from Quantum Computing Threats - Cisco Blogs - January 14th, 2026 [January 14th, 2026]
- PsiQuantum Collaborating with Airbus to Advance Quantum Computing for Aerospace - HPCwire - January 14th, 2026 [January 14th, 2026]
- Putting Quantum Computing to the Test - University of Pittsburgh - January 14th, 2026 [January 14th, 2026]
- Xanadu and Thorlabs Partner to Advance Optical Controls for Photonic Quantum Computing - HPCwire - January 14th, 2026 [January 14th, 2026]
- Why Quantum Computers Are Inherently Reversible (And Why That Matters) - Quantum Zeitgeist - January 14th, 2026 [January 14th, 2026]
- 1 Quantum Computing Stock to Buy that Could Soar in 2026 - The Motley Fool - January 14th, 2026 [January 14th, 2026]
- BTQ Technologies Added to VanEck Quantum Computing UCITS ETF, Expanding European Access to BTQ Through a Regulated UCITS Wrapper - PR Newswire - January 14th, 2026 [January 14th, 2026]
- Singapore and Japan team up on quantum computing - Computer Weekly - January 14th, 2026 [January 14th, 2026]
- Will Quantum Computing Stocks Become the AI Stocks of 2026? - The Motley Fool - January 14th, 2026 [January 14th, 2026]
- Silicon vibrations add a new twist to dark matter research and quantum computing - The Brighter Side of News - January 14th, 2026 [January 14th, 2026]
- D-Wave Just Got a Formidable Quantum Computing Ally. Should You Buy QBTS Stock Here? - Yahoo Finance - January 14th, 2026 [January 14th, 2026]
- 1 Quantum Computing Stock to Buy that Could Soar in 2026 - AOL.com - January 14th, 2026 [January 14th, 2026]
- Yaqumo Inc. and Entropica Labs Sign MOU, Witnessed by Singapore and Japan Governments, to Accelerate Fault-Tolerant Quantum Computing - The Quantum... - January 14th, 2026 [January 14th, 2026]
- Quantum Advantage Has Likely Been Achieved The Debate Is Over What Counts - The Quantum Insider - January 14th, 2026 [January 14th, 2026]
- Will quantum computing stocks become the AI stocks of 2026? - MSN - January 14th, 2026 [January 14th, 2026]
- Quantum Computing Stocks To Add to Your Watchlist - January 12th - MarketBeat - January 14th, 2026 [January 14th, 2026]
- Quantum computing revives debate over Bitcoins long-term security - Mugglehead Magazine - January 14th, 2026 [January 14th, 2026]
- Quantum AI: Telco's Next Big Thing or Expensive Distraction? - Telecoms - January 14th, 2026 [January 14th, 2026]
- What does a quantum computer sound like? This artist and scientist are about to find out - Financial Times - January 11th, 2026 [January 11th, 2026]
- Bipartisan Sens. Give Quantum Reauthorization Act Another Chance - MeriTalk - January 11th, 2026 [January 11th, 2026]
- 3 Quantum Computing Stocks That Could Make a Millionaire - The Motley Fool - January 9th, 2026 [January 9th, 2026]
- Infleqtion and Churchill X Move Forward on SPAC Combination - The Quantum Insider - January 9th, 2026 [January 9th, 2026]
- Quantum computing has advantages over traditional, but still in early innings: BMO (IONQ:NYSE) - Seeking Alpha - January 9th, 2026 [January 9th, 2026]
- D-Wave Buys Quantum Circuits in Shift to Higher Gear - EE Times - January 9th, 2026 [January 9th, 2026]
- Beyond the Hype: 5 Reasons Quantum Computing Stocks IonQ, Rigetti Computing, and D-Wave Quantum Can Crash in 2026 - Nasdaq - January 9th, 2026 [January 9th, 2026]
- Quantum neural network may be able to cheat the uncertainty principle - New Scientist - January 9th, 2026 [January 9th, 2026]
- Q&A: What does cybersecurity look like in the quantum age? - Penn State University - January 9th, 2026 [January 9th, 2026]
- D-Wave Demo At CES 2026 And The Energy Efficiency Of Quantum Computing - Quantum Zeitgeist - January 9th, 2026 [January 9th, 2026]
- Quantum Computers Extract Scattering Phase Shift In One-Dimensional Systems Using Integrated Correlation Functions - Quantum Zeitgeist - January 9th, 2026 [January 9th, 2026]
- How John Clarke's Nobel Prize-Winning Research Paved the Way for Quantum Computing - Berkeley Lab News Center (.gov) - January 9th, 2026 [January 9th, 2026]
- Circle Examines How Crypto and Web3 Ecosystems are Preparing Blockchains for the Quantum Era - Crowdfund Insider - January 9th, 2026 [January 9th, 2026]
- The Best Quantum Computing Stock to Buy Hand Over Fist in 2026 - The Motley Fool - January 9th, 2026 [January 9th, 2026]
- Quantum computing is closer than you think - Federal News Network - January 9th, 2026 [January 9th, 2026]
- Quantum computing company D-Wave acquires new tech in major merger - Washington Times - January 9th, 2026 [January 9th, 2026]
- Josephson junctions quantum computing building blocks are possible with only one superconductor, experiment confirms - Technology Org - January 9th, 2026 [January 9th, 2026]
- After a Year of Quantum Awareness, 2026 Becomes the Year of Quantum Security - The Quantum Insider - January 9th, 2026 [January 9th, 2026]
- The best quantum computing stock to buy hand over fist in 2026 - MSN - January 9th, 2026 [January 9th, 2026]
- Google Willow: The secrets of the world's most powerful quantum computer - BBC - January 8th, 2026 [January 8th, 2026]
- D-Wave: Quantums First Real Revenue Winner (NYSE:QBTS) - Seeking Alpha - January 8th, 2026 [January 8th, 2026]
- D-Wave to Buy Quantum Circuits for $550 Million. Useful Computers Are Coming to Market. - Barron's - January 8th, 2026 [January 8th, 2026]
- DARPA seeks universal translator between different kinds of quantum computer - Breaking Defense - January 8th, 2026 [January 8th, 2026]
- Royal Bank, Telus back $130-million financing by quantum developer Photonic - The Globe and Mail - January 8th, 2026 [January 8th, 2026]
- Qubits Can be Cloned: Scientists Discover First Method to Safely Back up Quantum Information - The Quantum Insider - January 8th, 2026 [January 8th, 2026]
- The Smartest Quantum Computing Stock to Buy for 2026 - Yahoo Finance - January 8th, 2026 [January 8th, 2026]
- 3 Top Quantum Computing Stocks to Buy in 2026 - The Motley Fool - January 8th, 2026 [January 8th, 2026]
- Fredkin And Toffoli: The Architects Of Reversible Computation - Quantum Zeitgeist - January 8th, 2026 [January 8th, 2026]
- Quantum Resistance LLC on the Future of Digital Security in a World of Emerging Quantum Computing - International Business Times - January 8th, 2026 [January 8th, 2026]
- Moscow State University and Rosatom Test 72-Qubit Neutral-Atom Quantum Prototype - Quantum Computing Report - January 8th, 2026 [January 8th, 2026]
- Prediction: These 4 quantum computing stocks will skyrocket in 2026 - MSN - January 8th, 2026 [January 8th, 2026]
- D-Wave Rises On Quantum First - Yahoo Finance - January 8th, 2026 [January 8th, 2026]
- Are Quantum Computing ETFs the Safest Bet for 10-Year Growth? - Nasdaq - January 8th, 2026 [January 8th, 2026]
- Tech and compliance 2026: What to watch for in AI, cybersecurity and quantum computing - Compliance Week - January 8th, 2026 [January 8th, 2026]
- Using microwave pulses to plug leaks in quantum computers makes them more reliable - Phys.org - December 29th, 2025 [December 29th, 2025]
- 5 Major Quantum Computing Breakthroughs that Shaped 2025 - TipRanks - December 29th, 2025 [December 29th, 2025]
- D-Wave stock slides into year-end as quantum peers retreat in thin trade - ts2.tech - December 29th, 2025 [December 29th, 2025]
- Quantum Computing Trends in 2025: Data Reveals Hardware Bets, Cloud Growth And Security Focus - The Quantum Insider - December 29th, 2025 [December 29th, 2025]
- The Neglecton: How Mathematical 'Garbage' Saved The Quantum Computer - Quantum Zeitgeist - December 29th, 2025 [December 29th, 2025]
- Quantum science and technology: highlights of 2025 - Physics World - December 29th, 2025 [December 29th, 2025]
- Are These 2 Quantum Computing Stocks the Key to Decades of Wealth? - The Motley Fool - December 29th, 2025 [December 29th, 2025]
- The Man Who Knew Too Much: Why Ettore Majoranas 1938 disappearance still haunts quantum computing. - Quantum Zeitgeist - December 29th, 2025 [December 29th, 2025]
- Breaking The Code: How Peter Shor Proved Quantum Power Was Real - Quantum Zeitgeist - December 29th, 2025 [December 29th, 2025]
- Opinion: Quantum computing is the stock markets next big tech play and these stocks are still cheap - MarketWatch - December 29th, 2025 [December 29th, 2025]
- Quantum computing made measurable progress toward real-world use in 2025 - TechSpot - December 29th, 2025 [December 29th, 2025]
- IonQ drops with quantum peers into year-end, as investors weigh next catalysts - ts2.tech - December 29th, 2025 [December 29th, 2025]
- Forget Rigetti Computing: This Quantum Stock Offers a Far Better Risk-Reward Right Now - Finviz - December 29th, 2025 [December 29th, 2025]
- Quantum Computing Stocks: IonQ, Rigetti, D-Wave and QUBT Slide Into Year-EndWhat to Watch Before Mondays Open - ts2.tech - December 29th, 2025 [December 29th, 2025]