COPPER

A PS Audio Publication

Issue 221 • Free Online Magazine

Issue 221 Featured

Quantum Technology and the Future of Music and Audio

Quantum Technology and the Future of Music and Audio

2001: A Space Odyssey is a film which greatly influenced my future. The movie's HAL 9000 computer may or may not have been thinly veiled as a fictional IBM creation  HAL’s initials are one letter apart from IBM’s. It likely influenced an entire generation of the populace to fear a computer. Not me. (The film's creators say the name was not intended to be a play on IBM.) Indeed, during my job interview at a wafer fab (chip-making plant), I noted to management, “IBM uses a computer to make a computer.” And into the world of wafers, ceramics and mainframes I went.

So, it was with anticipation that I heralded the announcement by IBM claiming the world's quickest quantum computer is only a few years away. [Their IBM Quantum Heron is a reality, featuring a 133-qubit processor, and the 10,000-qubit Starling is projected to be 20,000 time more powerful than anything available today, with an expected availability date of 2029 – Ed.]

 

IBM Quantum Lab in Yorktown Heights, New York. Courtesy of Connie Zhou/IBM.

 

But what is “quantum” anyway? Who cares? What might it mean to the future of music and audio? Intrigued, I spent one month digging into the possible future. Right, HAL?
I could wax poetic about a coming new world in technology that will revolutionize audio, like Maxell cassette tape or the Sony VCR, then the iPod, iPhone and computer downloads. Technology that is tested in the real world of economic survival.

Quantum technology delves into the realm of nuclear physics. While "classical" computer technology employs bits, two possible states that can be either on/off or 1/0 to represent information, quantum computer technology uses qubits which can be either 1/0 or both simultaneously – a phenomenon called superposition. Even more loveable, if you will: qubits can link up and “communicate” with each other, a circumstance called quantum entanglement.

What exactly do we mean by “quantum”? Who would be better to answer this than Dr. Brian Cox, an English physicist and musician who is professor of particle physics in the School of Physics and Astronomy at The University of Manchester. But I watched a video by Dr. Brian Cox on quantum physics and I admit I am more confused than before. Technically, quantum mechanics is the study of matter and its interaction with energy on a very small level, that of atomic and subatomic particles. On this level, things behave in often-unexpected ways compared to the classical physics we were taught in school. Along with quantum entanglement, perhaps the most unexpected is the uncertainly principle: with certain pairs of physical properties, the less accurately the other can be known.

 

 

The study of quantum phenomena requires technologies like lasers and advanced detectors and ways to excite an atom’s electron orbits to jump or fall or, like Dr. Cox says, to spin. The only spin I know is the jazz vinyl on the turntable. Yet those nuclei are smart enough to obey physical laws of nature.

But aside from their ability to inspire and even awe, quantum machines have their set of problems. Of course, they have. The major complication is, in theory, they are vulnerable to being penetrated by other quantum machines. Google halted research into its Willow quantum chip. IBM and Microsoft both remain tight-lipped about their efforts. I asked for a comment from IBM’s Thomas J. Watson Research Center in Yorktown Heights, New York. I did not receive a response. Research by other organizations has resulted in quantum computers producing unexpected results, causing the organizations to take a step back.

I worked on the assembly of mainframe computers – liquid-cooled, with hardware hung inside static-electricity-proof frames; in a word, exotic. Quantum machines ingest vast sums of data at blinding speeds (IBM offers quantum-computing speeds on their machines on their website) and one can only wonder about what these machines might look like a few years from now, to say nothing of their applications, should their engineering problems be solved.

The Walt Disney Company has a history of innovation in animation and other arenas, such as their early adoption of CGI (computer-generated imagery), and this seems to be but one of many obvious commercial applications of quantum computing. But in my search efforts, I could not find evidence to indicate they employ quantum computing in active operations or research. 

The media and entertainment industries are undoubtedly exploring the potentials of quantum computing. Some possible applications include: 

•    Enhanced visual effects: A quantum computer could lead to more realistic and complex simulations of light and other physical phenomena for movies and special effects.
•    Faster rendering: A quantum computer could accelerate video editing and rendering processes.
•    Improved content personalization and recommendations: quantum algorithms could enhance audience analytics and make for more targeted personalized content delivery. 

While right now no public information exists that Walt Disney has possibly explored quantum computing behind the scenes, it’s worth noting that a Donald Duck comic book features a character who installs a dilution refrigerator for their quantum computer. Fiction today, reality tomorrow?
 
On the audio front: I recently read that Bowers and Wilkins released the 801 Abbey Road Limited Edition loudspeaker, priced at $70,000 per pair. I would rob a bank to buy those. But ought I? What advancements might be coming next? I have imagined a thin opaque-film transducer taking the place of conventional speakers. Or amplifiers that weigh less than 10 pounds. Or an infinite playlist tailored to what I like. Is this future possible with quantum technology?

 

 

B&W 801 Abbey Road limited edition loudspeakers.

 

I recently read an article that detailed the 35 most costly speakers in the high-end world, priced from $80,000 – $1,200,000 per pair. Many had huge exotic cabinets…but with round speakers. Sure, made from exotic materials, but sound produced with cone technology. I think there’s a lot of room for advancement, even in planar and electrostatic designs. And I want the $1.2 million aural texture that such speaker provide…at 1/1,000th the price.

I set about to find an expert in quantum technology to learn more about its potential applications in music and audio, and I found one: Dr. Sukwoong Choi of the Massry School of Business at The University at Albany, and MIT. Here’s what we discussed. 
 
Joseph Caplan: What impact, if any, will quantum computing have on music production?

Dr. Sukwoong Choi: At this stage, quantum computing is unlikely to impact mainstream music production workflows in the near term. Digital audio workstations (DAWs), real-time audio processing, and mixing rely on well-optimized classical algorithms that are already fast and cost-effective. However, in the longer term, quantum computing could aid in generative music models that require navigating extremely large combinatorial spaces – such as composing music that optimally evokes certain emotions or follows intricate aesthetic constraints. In particular, quantum-enhanced sampling or optimization (e.g., via quantum annealing or variational circuits) may augment generative AI models that are currently bottlenecked by classical approximations.
 
JC: Will it have any impact on music composition?

Dr. SC: Yes, potentially. Music composition, especially algorithmic composition or AI-assisted composition, involves exploring vast musical idea spaces with complex constraints (harmony, progression, emotion, genre rules). Quantum computing could offer a speed-up in searching these spaces or in simulating systems like quantum-inspired harmony engines, particularly in avant-garde or research contexts. Think of a composer training a generative model that creates entirely new forms of music blending diverse traditions. Quantum algorithms may be used to explore creative constraints that classical computers struggle to represent simultaneously.
 
JC: How about electronic circuit design and simulation?

Dr. SC: Quantum computing holds strong potential in circuit design, but only under specific conditions where quantum advantage is achievable. Classical simulation of quantum phenomena – such as electron behavior in molecules or superconducting junctions – is computationally intractable at scale. Quantum computers can natively model these systems, offering breakthroughs in materials discovery and nanoscale component design, such as transistors or superconducting interconnects. However, as outlined in my paper (Choi et al., 2025; reference below), such advantages depend on the complexity of the design problem, the structure of the search space, and whether the problem fits quantum-efficient algorithms. When these conditions are met, quantum computing could enhance electronic design automation (EDA) and possibly contribute to ultra-low-noise or high-fidelity audio hardware.
 
JC: Are there any implications for the manufacture of playback equipment – perhaps speaker design?

Dr. SC: Quantum computing may accelerate materials discovery for audio components. For example, simulating atomic structures of magnets or polymers could lead to better drivers and membranes in speakers. This wouldn't create a “quantum speaker” [per se], but it could improve fidelity, efficiency, and weight. These benefits would emerge indirectly through quantum-enabled materials science.

JC: Why should the average person care? What impact will supercomputing have on everyday listeners?

Dr. SC: Quantum computing’s greatest impact on music for the average person may come from behind the scenes. Improvements in audio compression, streaming optimization, or personalized music recommendation systems could stem from hybrid quantum-classical algorithms.
 
Moreover, when quantum-enhanced AI models become better at understanding emotional responses to music, the curation of music libraries could become more tailored and emotionally intelligent – improving how people discover and engage with sound.
 
JC: Could quantum computing accommodate materials science, acoustic data sets, and other variables to revolutionize music as we know it?

Dr. SC: Yes – in the long run. Quantum computing excels at simulating quantum-mechanical systems, including materials used in audio hardware or even neural processes in auditory perception. These capabilities could eventually transform materials science, psychoacoustics, and nonlinear signal modeling, leading to new forms of personalized acoustics or immersive VR/AR audio experiences.

However, as outlined in my research, such transformations depend on whether the problems involved are classically hard, structurally compatible with quantum algorithms, and sensitive to precision at quantum scales. If these conditions are met, quantum advantage becomes possible – but practical impacts for everyday listeners are likely a decade or more away.

 The paper Dr. Choi references is the following: CHOI, S., MOSES, W. S., & THOMPSON, N. (2025). The Quantum Tortoise and the Classical Hare: When Will Quantum Computers Outpace Classical Ones and When Will They Be Left Behind? Proceedings of the IEEE, 1–12. https://doi.org/10.1109/JPROC.2025.3574102

The last word: while at IBM I had to learn fast in a digital world of 1s and 0s. But at the subatomic level, Qubits function at both states. What will become possible in the audio universe from a new computing paradigm? Well, Dr. Choi suggests a decade-long wait. It’s enough to make me want to rob a bank to purchase that pair of B&W speakers.

 

About Joseph Caplan: In the 1960s my mother went grocery shopping at Grand Union. They issued S&H Green Stamps, redeemable at their gift center next door. I fastidiously pasted those stamps into the booklets and excitedly traded them for my first Japanese transistor radio. I've been hooked on audio ever since.


Header image courtesy of Pixabay.com/geralt.

More from Issue 221

View All Articles in Issue 221

Search Copper Magazine

#227 Seth Lewis Gets in the Groove With Take a Look Around: a Tribute to the Meters by Frank Doris Feb 02, 2026 #227 Passport to Sound: May Anwar’s Audio Learning Experience for Young People by Frank Doris Feb 02, 2026 #227 Conjectures on Cosmic Consciousness by B. Jan Montana Feb 02, 2026 #227 The Big Takeover Turns 45 by Wayne Robins Feb 02, 2026 #227 Music and Chocolate: On the Sensory Connection by Joe Caplan Feb 02, 2026 #227 Singer/Songwriter Chris Berardo: Getting Wilder All the Time by Ray Chelstowski Feb 02, 2026 #227 The Earliest Stars of Country Music, Part One by Jeff Weiner Feb 02, 2026 #227 The Vinyl Beat Goes Down to Tijuana (By Way of Los Angeles), Part Two by Rudy Radelic Feb 02, 2026 #227 How to Play in a Rock Band, 20: On the Road With Blood, Sweat & Tears’ Guitarist Gabe Cummins by Frank Doris Feb 02, 2026 #227 From The Audiophile’s Guide: Audio Specs and Measuring by Paul McGowan Feb 02, 2026 #227 Our Brain is Always Listening by Peter Trübner Feb 02, 2026 #227 PS Audio in the News by PS Audio Staff Feb 02, 2026 #227 The Listening Chair: Sleek Style and Sound From the Luxman L3 by Howard Kneller Feb 02, 2026 #227 The Los Angeles and Orange County Audio Society Celebrates Its 32nd Anniversary, Honoring David and Sheryl Lee Wilson and Bernie Grundman by Harris Fogel Feb 02, 2026 #227 Back to My Reel-to-Reel Roots, Part 26: Half Full – Not Half Empty, Redux by Ken Kessler Feb 02, 2026 #227 That's What Puzzles Us... by Frank Doris Feb 02, 2026 #227 Record-Breaking by Peter Xeni Feb 02, 2026 #227 The Long and Winding Road by B. Jan Montana Feb 02, 2026 #226 JJ Murphy’s Sleep Paralysis is a Genre-Bending Musical Journey Through Jazz, Fusion and More by Frank Doris Jan 05, 2026 #226 Stewardship by Consent by B. Jan Montana Jan 05, 2026 #226 Food, Music, and Sensory Experience: An Interview With Professor Jonathan Zearfoss of the Culinary Institute of America by Joe Caplan Jan 05, 2026 #226 Studio Confidential: A Who’s Who of Recording Engineers Tell Their Stories by Frank Doris Jan 05, 2026 #226 Pilot Radio is Reborn, 50 Years Later: Talking With CEO Barak Epstein by Frank Doris Jan 05, 2026 #226 The Vinyl Beat Goes Down to Tijuana (By Way of Los Angeles), Part One by Rudy Radelic Jan 05, 2026 #226 Capital Audiofest 2025: Must-See Stereo, Part Two by Frank Doris Jan 05, 2026 #226 My Morning Jacket’s Carl Broemel and Tyler Ramsey Collaborate on Their Acoustic Guitar Album, Celestun by Ray Chelstowski Jan 05, 2026 #226 The People Who Make Audio Happen: CanJam SoCal 2025, Part Two by Harris Fogel Jan 05, 2026 #226 How to Play in a Rock Band, 19: Touring Can Make You Crazy, Part One by Frank Doris Jan 05, 2026 #226 Linda Ronstadt Goes Bigger by Wayne Robins Jan 05, 2026 #226 From The Audiophile’s Guide: Active Room Correction and Digital Signal Processing by Paul McGowan Jan 05, 2026 #226 PS Audio in the News by Frank Doris Jan 05, 2026 #226 Back to My Reel-to-Reel Roots, Part 25: Half-Full, Not Empty by Ken Kessler Jan 05, 2026 #226 Happy New Year! by Frank Doris Jan 05, 2026 #226 Turn It Down! by Peter Xeni Jan 05, 2026 #226 Ghost Riders by James Schrimpf Jan 05, 2026 #226 A Factory Tour of Audio Manufacturer German Physiks by Markus "Marsu" Manthey Jan 04, 2026 #225 Capital Audiofest 2025: Must-See Stereo, Part One by Frank Doris Dec 01, 2025 #225 Otis Taylor and the Electrics Delivers a Powerful Set of Hypnotic Modern Blues by Frank Doris Dec 01, 2025 #225 A Christmas Miracle by B. Jan Montana Dec 01, 2025 #225 T.H.E. Show New York 2025, Part Two: Plenty to See, Hear, and Enjoy by Frank Doris Dec 01, 2025 #225 Underappreciated Artists, Part One: Martin Briley by Rich Isaacs Dec 01, 2025 #225 Rock and Roll is Here to Stay by Wayne Robins Dec 01, 2025 #225 A Lifetime of Holiday Record (and CD) Listening by Rudy Radelic Dec 01, 2025 #225 Little Feat: Not Saying Goodbye, Not Yet by Ray Chelstowski Dec 01, 2025 #225 How to Play in a Rock Band, Part 18: Dealing With Burnout by Frank Doris Dec 01, 2025 #225 The People Who Make Audio Happen: CanJam SoCal 2025 by Harris Fogel Dec 01, 2025 #225 Chicago’s Sonic Sanctuaries: Four Hi‑Fi Listening Bars Channeling the Jazz‑Kissa Spirit by Olivier Meunier-Plante Dec 01, 2025

Quantum Technology and the Future of Music and Audio

Quantum Technology and the Future of Music and Audio

2001: A Space Odyssey is a film which greatly influenced my future. The movie's HAL 9000 computer may or may not have been thinly veiled as a fictional IBM creation  HAL’s initials are one letter apart from IBM’s. It likely influenced an entire generation of the populace to fear a computer. Not me. (The film's creators say the name was not intended to be a play on IBM.) Indeed, during my job interview at a wafer fab (chip-making plant), I noted to management, “IBM uses a computer to make a computer.” And into the world of wafers, ceramics and mainframes I went.

So, it was with anticipation that I heralded the announcement by IBM claiming the world's quickest quantum computer is only a few years away. [Their IBM Quantum Heron is a reality, featuring a 133-qubit processor, and the 10,000-qubit Starling is projected to be 20,000 time more powerful than anything available today, with an expected availability date of 2029 – Ed.]

 

IBM Quantum Lab in Yorktown Heights, New York. Courtesy of Connie Zhou/IBM.

 

But what is “quantum” anyway? Who cares? What might it mean to the future of music and audio? Intrigued, I spent one month digging into the possible future. Right, HAL?
I could wax poetic about a coming new world in technology that will revolutionize audio, like Maxell cassette tape or the Sony VCR, then the iPod, iPhone and computer downloads. Technology that is tested in the real world of economic survival.

Quantum technology delves into the realm of nuclear physics. While "classical" computer technology employs bits, two possible states that can be either on/off or 1/0 to represent information, quantum computer technology uses qubits which can be either 1/0 or both simultaneously – a phenomenon called superposition. Even more loveable, if you will: qubits can link up and “communicate” with each other, a circumstance called quantum entanglement.

What exactly do we mean by “quantum”? Who would be better to answer this than Dr. Brian Cox, an English physicist and musician who is professor of particle physics in the School of Physics and Astronomy at The University of Manchester. But I watched a video by Dr. Brian Cox on quantum physics and I admit I am more confused than before. Technically, quantum mechanics is the study of matter and its interaction with energy on a very small level, that of atomic and subatomic particles. On this level, things behave in often-unexpected ways compared to the classical physics we were taught in school. Along with quantum entanglement, perhaps the most unexpected is the uncertainly principle: with certain pairs of physical properties, the less accurately the other can be known.

 

 

The study of quantum phenomena requires technologies like lasers and advanced detectors and ways to excite an atom’s electron orbits to jump or fall or, like Dr. Cox says, to spin. The only spin I know is the jazz vinyl on the turntable. Yet those nuclei are smart enough to obey physical laws of nature.

But aside from their ability to inspire and even awe, quantum machines have their set of problems. Of course, they have. The major complication is, in theory, they are vulnerable to being penetrated by other quantum machines. Google halted research into its Willow quantum chip. IBM and Microsoft both remain tight-lipped about their efforts. I asked for a comment from IBM’s Thomas J. Watson Research Center in Yorktown Heights, New York. I did not receive a response. Research by other organizations has resulted in quantum computers producing unexpected results, causing the organizations to take a step back.

I worked on the assembly of mainframe computers – liquid-cooled, with hardware hung inside static-electricity-proof frames; in a word, exotic. Quantum machines ingest vast sums of data at blinding speeds (IBM offers quantum-computing speeds on their machines on their website) and one can only wonder about what these machines might look like a few years from now, to say nothing of their applications, should their engineering problems be solved.

The Walt Disney Company has a history of innovation in animation and other arenas, such as their early adoption of CGI (computer-generated imagery), and this seems to be but one of many obvious commercial applications of quantum computing. But in my search efforts, I could not find evidence to indicate they employ quantum computing in active operations or research. 

The media and entertainment industries are undoubtedly exploring the potentials of quantum computing. Some possible applications include: 

•    Enhanced visual effects: A quantum computer could lead to more realistic and complex simulations of light and other physical phenomena for movies and special effects.
•    Faster rendering: A quantum computer could accelerate video editing and rendering processes.
•    Improved content personalization and recommendations: quantum algorithms could enhance audience analytics and make for more targeted personalized content delivery. 

While right now no public information exists that Walt Disney has possibly explored quantum computing behind the scenes, it’s worth noting that a Donald Duck comic book features a character who installs a dilution refrigerator for their quantum computer. Fiction today, reality tomorrow?
 
On the audio front: I recently read that Bowers and Wilkins released the 801 Abbey Road Limited Edition loudspeaker, priced at $70,000 per pair. I would rob a bank to buy those. But ought I? What advancements might be coming next? I have imagined a thin opaque-film transducer taking the place of conventional speakers. Or amplifiers that weigh less than 10 pounds. Or an infinite playlist tailored to what I like. Is this future possible with quantum technology?

 

 

B&W 801 Abbey Road limited edition loudspeakers.

 

I recently read an article that detailed the 35 most costly speakers in the high-end world, priced from $80,000 – $1,200,000 per pair. Many had huge exotic cabinets…but with round speakers. Sure, made from exotic materials, but sound produced with cone technology. I think there’s a lot of room for advancement, even in planar and electrostatic designs. And I want the $1.2 million aural texture that such speaker provide…at 1/1,000th the price.

I set about to find an expert in quantum technology to learn more about its potential applications in music and audio, and I found one: Dr. Sukwoong Choi of the Massry School of Business at The University at Albany, and MIT. Here’s what we discussed. 
 
Joseph Caplan: What impact, if any, will quantum computing have on music production?

Dr. Sukwoong Choi: At this stage, quantum computing is unlikely to impact mainstream music production workflows in the near term. Digital audio workstations (DAWs), real-time audio processing, and mixing rely on well-optimized classical algorithms that are already fast and cost-effective. However, in the longer term, quantum computing could aid in generative music models that require navigating extremely large combinatorial spaces – such as composing music that optimally evokes certain emotions or follows intricate aesthetic constraints. In particular, quantum-enhanced sampling or optimization (e.g., via quantum annealing or variational circuits) may augment generative AI models that are currently bottlenecked by classical approximations.
 
JC: Will it have any impact on music composition?

Dr. SC: Yes, potentially. Music composition, especially algorithmic composition or AI-assisted composition, involves exploring vast musical idea spaces with complex constraints (harmony, progression, emotion, genre rules). Quantum computing could offer a speed-up in searching these spaces or in simulating systems like quantum-inspired harmony engines, particularly in avant-garde or research contexts. Think of a composer training a generative model that creates entirely new forms of music blending diverse traditions. Quantum algorithms may be used to explore creative constraints that classical computers struggle to represent simultaneously.
 
JC: How about electronic circuit design and simulation?

Dr. SC: Quantum computing holds strong potential in circuit design, but only under specific conditions where quantum advantage is achievable. Classical simulation of quantum phenomena – such as electron behavior in molecules or superconducting junctions – is computationally intractable at scale. Quantum computers can natively model these systems, offering breakthroughs in materials discovery and nanoscale component design, such as transistors or superconducting interconnects. However, as outlined in my paper (Choi et al., 2025; reference below), such advantages depend on the complexity of the design problem, the structure of the search space, and whether the problem fits quantum-efficient algorithms. When these conditions are met, quantum computing could enhance electronic design automation (EDA) and possibly contribute to ultra-low-noise or high-fidelity audio hardware.
 
JC: Are there any implications for the manufacture of playback equipment – perhaps speaker design?

Dr. SC: Quantum computing may accelerate materials discovery for audio components. For example, simulating atomic structures of magnets or polymers could lead to better drivers and membranes in speakers. This wouldn't create a “quantum speaker” [per se], but it could improve fidelity, efficiency, and weight. These benefits would emerge indirectly through quantum-enabled materials science.

JC: Why should the average person care? What impact will supercomputing have on everyday listeners?

Dr. SC: Quantum computing’s greatest impact on music for the average person may come from behind the scenes. Improvements in audio compression, streaming optimization, or personalized music recommendation systems could stem from hybrid quantum-classical algorithms.
 
Moreover, when quantum-enhanced AI models become better at understanding emotional responses to music, the curation of music libraries could become more tailored and emotionally intelligent – improving how people discover and engage with sound.
 
JC: Could quantum computing accommodate materials science, acoustic data sets, and other variables to revolutionize music as we know it?

Dr. SC: Yes – in the long run. Quantum computing excels at simulating quantum-mechanical systems, including materials used in audio hardware or even neural processes in auditory perception. These capabilities could eventually transform materials science, psychoacoustics, and nonlinear signal modeling, leading to new forms of personalized acoustics or immersive VR/AR audio experiences.

However, as outlined in my research, such transformations depend on whether the problems involved are classically hard, structurally compatible with quantum algorithms, and sensitive to precision at quantum scales. If these conditions are met, quantum advantage becomes possible – but practical impacts for everyday listeners are likely a decade or more away.

 The paper Dr. Choi references is the following: CHOI, S., MOSES, W. S., & THOMPSON, N. (2025). The Quantum Tortoise and the Classical Hare: When Will Quantum Computers Outpace Classical Ones and When Will They Be Left Behind? Proceedings of the IEEE, 1–12. https://doi.org/10.1109/JPROC.2025.3574102

The last word: while at IBM I had to learn fast in a digital world of 1s and 0s. But at the subatomic level, Qubits function at both states. What will become possible in the audio universe from a new computing paradigm? Well, Dr. Choi suggests a decade-long wait. It’s enough to make me want to rob a bank to purchase that pair of B&W speakers.

 

About Joseph Caplan: In the 1960s my mother went grocery shopping at Grand Union. They issued S&H Green Stamps, redeemable at their gift center next door. I fastidiously pasted those stamps into the booklets and excitedly traded them for my first Japanese transistor radio. I've been hooked on audio ever since.


Header image courtesy of Pixabay.com/geralt.

0 comments

Leave a comment

0 Comments

Your avatar

Loading comments...

🗑️ Delete Comment

Enter moderator password to delete this comment:

✏️ Edit Comment

Enter your email to verify ownership: