Quantum Communications - Part 3: Photon Polarization and Superposition

 Building on Part 2’s discussion of polarization, let's look a little deeper at how light enables quantum communication. Superposition in quantum mechanics means a photon can exist in multiple polarization states at once, unlike classical objects that must be in one definite state. Looking at the diagram below, a photon isn't limited to being just vertical (1) or horizontal (0), but can exist in a mixture of both until measured. Think of it like a spinning coin - while spinning, it's neither heads nor tails but both possibilities at once. When we measure the photon's polarization (like catching the coin), it "collapses" into one definite state.

The diagram shows two measurement bases - rectilinear and diagonal. A photon in superposition measured in either base has a probability of being found in either state of that base. This property is crucial for quantum cryptography because any measurement by an eavesdropper forces the superposition to collapse, altering the photon's state and revealing the intrusion.

 

The 45° polarization state, shown in the diagonal base of our diagram, demonstrates one of the most fascinating aspects of quantum mechanics. While we might classically think of 45° as simply an angle halfway between horizontal and vertical, in quantum mechanics it represents something far more profound. When a photon is polarized at 45°, it literally exists in a perfect blend of horizontal and vertical states at the same time - not just leaning one way or the other, but fully in both states simultaneously.

 

This quantum behavior becomes clear when we measure these 45° polarized photons. If we measure using the rectilinear base (horizontal/vertical as shown in the left circle of our diagram), we get the following result: the photon will randomly show up as either horizontal or vertical with exactly equal probability. This isn't because we're measuring imprecisely or because the photon was "kind of" in both states - it was genuinely, mathematically, and physically in both states at once until the act of measurement forced it to pick one.

 

Think of it this way: if we send many 45° polarized photons through a horizontal polarizer, exactly half will pass through (registering as horizontal) and half will be blocked (registering as vertical). This isn't due to some classical "angled" behavior - it's a direct manifestation of quantum superposition, where the photon existed in both states simultaneously until we forced it to "decide" by measuring it.

 

This property is part of what makes quantum communication so secure: any attempt to measure these superposition states unavoidably disturbs them, making eavesdropping detectable.

Quantum Communications - Part 2: Polarization

In Part 1 of this series I discussed how quantum superposition allows particles to exist in multiple states at once until measured. This makes quantum information almost impossible to copy secretly, enabling ultra-secure communication systems that can detect eavesdropping attempts. Here we'll take a closer look at how this information is transmitted using light particles called photons. 

Light can be analyzed as either a ray or a wave, each model revealing different aspects of its behavior. The ray model treats light as straight lines traveling through space, useful for understanding reflection, refraction, and how lenses and mirrors work. The wave model shows light as oscillating electromagnetic waves, explaining phenomena like interference, diffraction, and polarization. While the ray model helps us design simple optical devices like eyeglasses, the wave model is necessary for understanding more complex effects like how polarizing filters work. Both models remain important in modern optics, with each being used depending on which aspects of light's behavior are most relevant to the situation at hand.

 

When it comes to polarization we need to think about light as a wave. Light waves oscillate perpendicular to their direction of travel, Unpolarized light ( like we get from natural sources like the sun or artificial sources like light bulbs) vibrates in all possible directions like a rope being waved up-down, side-to-side, and at every angle in between. A polarization filter works like a microscopic venetian blind with extremely fine parallel slits. When light encounters the filter, only the waves that vibrate parallel to these slits can pass through completely. Waves vibrating in other directions are either blocked entirely or have only their parallel components transmitted. The light that emerges from the filter is polarized, meaning all the waves are vibrating in the same direction. 

Here's a quick 3 second video I made demonstrating light passing through a polarizing filter.

Before the filter: 

• Horizontal component (blue wave)
• Vertical component (pink wave)
• 45-degree component (green wave, thicker line) All components are present in the unpolarized light

The Filter: 

• Oriented at 45 degrees
• Only allows waves aligned with its transmission axis

After the filter: 

• Only the 45-degree component (green wave) passes through
• Horizontal and vertical components are blocked
• The transmitted light is polarized along the 45-degree axis

Notice:

• Only transmits light waves that oscillate parallel to its transmission axis (45 degrees in this case)
• Waves at other angles are either blocked or have only their 45-degree component transmitted
• The result is polarized light oscillating only at 45 degrees

This selective transmission property makes polarizing filters particularly useful in everyday applications. For example, polarizing sunglasses can effectively reduce glare because light reflecting off horizontal surfaces like water or roads tends to become partially polarized in the horizontal direction. The sunglasses, which have vertical polarizing slits, block this horizontal glare while still allowing other light through. A demonstration of how polarization works involves using two polarizing filters. When light passes through the first filter, it becomes polarized in one direction. If you then rotate a second filter 90 degrees relative to the first, no light gets through at all because the polarized light from the first filter is now perpendicular to the slits in the second filter.

 

So what does polarization have to do with quantum communications? In quantum communications individual photons can be prepared in specific polarization states (vertical, horizontal, or diagonal) to represent quantum bits. Due to quantum mechanics principles, any attempt to measure these polarization states disturbs them, making secure communication possible - eavesdropping can be detected. Polarization also enables quantum entanglement, where measuring one photon's polarization instantly determines its entangled partner's state, even at a distance.

 

While powerful, polarization methods face practical challenges as polarization states can degrade during transmission through optical fibers or atmosphere, requiring sophisticated error correction methods. For these reasons, quantum communications can use several alternatives to polarization for encoding quantum information. Time-bin encoding uses photon arrival times and works well in fiber optics where polarization degrades. Phase encoding utilizes phase differences between photon paths, while frequency encoding uses different photon frequencies. Orbital Angular Momentum (OAM) encoding exploits spiral patterns of light waves, potentially carrying more information than polarization. Path encoding, which uses different physical routes for photons, is useful in integrated photonic circuits. Each of these methods has its own advantages and the choice often depends on the specific application and transmission medium being used. For instance, time-bin encoding tends to be more robust for long-distance fiber communication, while OAM can potentially carry more information per photon. 

Quantum Communications – Part 1

 Computers, communications, photonics, cybersecurity…… some of my favorite technologies all bundled together in quantum communications! But… what is it? How does it work? Let's take an introductory look.

In quantum mechanics, something called superposition allows systems to exist in multiple states simultaneously - like a spinning coin being both heads and tails at once, until observed. Only measurement forces it into a definite state. This principle affects quantum information through the no-cloning theorem, which states that it's impossible to create an exact copy of an unknown quantum state due to quantum mechanics' mathematical foundations. This feature enables quantum key distribution (QKD), which creates unbreakable encryption keys. Any eavesdropping attempt disturbs the quantum states due to the no-cloning theorem, instantly revealing the intrusion. While classical information can be copied perfectly, quantum information's resistance to copying both protects it and makes quantum teleportation the only way to transfer quantum states.

 

How about an example? Let’s now compare sending a classical letter and sending a quantum letter using two diagrams I’ve created. These diagrams split into two parallel workflows showing classical versus quantum communication highlight the key security advantages of quantum communication over classical methods.

 

The classical letter path shows a letter that can be intercepted, read, and copied without detection as it moves from sender to recipient through the postal system.

The quantum letter path illustrates how quantum letters behave differently:

• The letter exists in superposition (blue state) until measured
• Any attempt to read/copy disturbs the quantum state (changes to red)
• This disturbance is detectable when received by the recipient, revealing tampering

We’ll dig a little deeper in future posts – for now think of quantum communication as the first step toward a quantum internet - one that operates on the powerful principles of quantum physics rather than classical physics. While we may not see quantum email on our phones anytime soon, the technology is steadily advancing from science fiction toward practical reality.

Pushing Optics Closer to the CPU

There's something very important I forgot to tell you! Don't cross the streams… It would be bad… Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

—Egon Spengler (Harold Ramis) on crossing proton streams, Ghostbusters

Well.... as we learned later in the movie, crossing streams is not always a bad thing.... As part of my work with the National Center for Optics and Photonics Education (OP-TEC: www.op-tec.org) I've been spending a lot of time learning new technical content while still staying current in the computing and communications field. I've been reading (and tweeting) recently about pushing optics closer and closer to the processor in computing systems. Here's more.

Last week, IBM announced the integration of a silicon photonic chip on the same package as a CPU. Why is this important? A couple of reasons -  if on-chip and chip-to-chip communications can use silicon as an optical medium, processing will be significantly faster, consume much less power and produce much less heat than the copper wires used today.

Extreme Tech published a nice diagram (below and based on the IBM announcement) last week showing the current state of silicon photonics technology. Notice the optical connection is currently at the board edge. With this IBM breakthrough, designers will begin to start moving the silicon photonics array closer and closer to the CPU, eventually building the optics into the CPU package itself.

The technology will initially be limited to the world of supercomputing but it will only be a matter of time before we see it trickle down to consumer level devices like PC's, tablets and smartphones. 

I love it when streams converge.

SDN: When The Hardware Becomes A Little More Soft

I grew up in the dedicated hardware world. Switches and routers that – sure - included processors and a little bit of memory.  Devices with pretty basic operating systems that kept track of addresses to move content around on a network, making sure stuff gets to where it is supposed to go. Nothing fancy but it has worked pretty good with the build out of the internet over the past 20 years or so. 

Today, we’re seeing a pretty major shift to what people are calling Software Defined Networks (SDNs). You may have seen SDN also referred to as elastic computing and/or elastic networks. The idea with SDNs is to not just try and make the network more efficient but also make it flexible and scalable. The concept is pretty simple and SDN Central explains it pretty well:

Software Defined Networking (SDN) is a new approach to designing, building and managing networks. The basic concept is that SDN separates the network’s control (brains) and forwarding (muscle) planes to make it easier to optimize each. 

In this environment, a Controller acts as the “brains,” providing an abstract, centralized view of the overall network. Through the Controller, network administrators can quickly and easily make and push out decisions on how the underlying systems (switches, routers) of the forwarding plane will handle the traffic.

So, you’ve got a smart controller looking at the entire network including applications running on the end devices. The controller communicates with network controlling devices (switches and routers), adjusting and optimizing the network to real-time conditions. Sort of like a maître d / head waiter in a busy restaurant.

For providers (Verizon, AT&T, etc) , SDNs reduce equipment costs and allow the networks to be more efficiently controlled. These networks are optical fiber-based and that has me pretty excited with my new position at the NSF-funded OP-TEC ATE Center. 

Centralized, programmable optical networks that dynamically adjust to changing requirements. Nice. I’ll be writing more about SDN and a number of other optics based technologies in future posts.

Massachusetts Green High Performance Computing Center (MGHPCC) - June 2012

I've written in the past about the Massachusetts Green High Performance Computing Center (MGHPCC) in Holyoke, MA. The project is a collaboration of five of the state’s most research-intensive universities (Boston University, Harvard, MIT, UMass Amherst and Northeastern), state government and private industry — the most significant collaboration among government, industry and public and private universities in the history of the Commonwealth, and the first facility in the nation of its kind.

The facility is currently under construction and when completed will provide a world-class computational infrastructure, indispensible in the increasingly sensor and data-rich environments of modern science and engineering discovery. Today, virtually no major breakthrough, be it designing a new drug, developing new materials for clean energy or addressing climate change -- can take place without computation. In silico experimentation adds a powerful new dimension to knowledge discovery in all fields, alongside theory, physical experimentation and observation. With the increasingly integrated role of computation in fundamental and applied research, the MGHPCC represents a critical piece of infrastructure that will continue to fuel the world-leading innovation economy of the Commonwealth of Massachusetts through cooperative research, education and outreach activities.

On Wednesday afternoon a group of got to tour the construction site. Here's my picture set.



We all left with our jaws hanging. An incredible facility and some amazing people doing some things nobody else has ever done. Thanks especially to Claire and John.

New UMass President and Massachusetts Green High Performance Computing Center

I've written in the past about high performance computing in Western Massachusetts. 

I had the opportunity today to visit the Massachusetts Green High Performance Computing Center (MGHPCC) in Holyoke, MA. A small group of us toured the Center with new University of Massachusetts President Robert Caret. 
As a UMass Amherst grad (Class of 1979) I have to admit it was pretty cool to be among the group to introduce Dr Caret to High Performance Computing in the Pioneer Valley. I'd like to thank MGHPCC Executive Director John Goodhue for the invite to this special event. Here's a few pics I snapped during the tour. 

Mass Green High Perf Computing Center, a set on Flickr.

Go UMass! Go MGHPCC!

Tropical storm Irene and The Connecticut River

This was my first week back from vacation and it was a busy one both inside and outside the office. Tropical Storm Irene came through last weekend and the flooding after really did some terrible damage and continues to impact people's lives from North Carolina to Maine..

Much of the rain that fell north of us from Irene eventually ended up flowing down the Connecticut River that separates Vermont and New Hampshire and splits Massachusetts and Connecticut. I drive by the Holyoke Dam every day going to and returning from work and took a few minutes to shoot some video on August 30, the day the river crested. I have never seen the river this high and this powerful. This was shot on the bridge connecting Holyoke and South Hadley Falls.



I could not believe the debris along with the color of the water.

Google Chromebook Coming Wednesday, June 15

On Wednesday, Google Chrome netbooks will start shipping. You can currently pre-order a Chrome netbook (Chromebook) at Amazon and Best Buy. The Chromebook concept was first described by Google a couple of years ago - before the iPad explosion. Here's some details on the Chromebooks shipping in the United States on June 15, 2011:

• Most have 11-12" screens and weigh a little over 3 pounds.
• They boot in 8 seconds and wake instantly from sleep mode.
• There is no license fee to the manufacturer for the operating system. In contrast, Microsoft charges $73 to a manufacturer for a Windows license.
• The devices have removable storage - Chrome supports USB memory and SD cards.
• Many of the devices will have high-definition webcams (e.g. Samsung and Acer models)
• Most manufactures are spec'ing a battery life of over 8 hours.
• Flash is supported (iPads and iPhones do not run flash).
• Wi-Fi only devices are selling for approximately $430 while Verizon 3G/Wi-Fi models are selling for $500.
• Google has created an online app store for Chrome. The store includes apps for Chromebooks and the Chrome browser (very nice - my default browser now) many of us are running on our regular computers.

Initially, running apps on a Chromebook will require online connectivity. Google says this summer they will be releasing versions of Gmail and Google Calendar that will run on the Chromebook while off-line. They are also offering app developers support to modify apps to run off-line.

The competition is heating up in the cloud space with the Apple's Lion OS X being released for $29 in July. Lion will more tightly integrate Apple PC's, iPads and iPhones using cloud based services.

Microsoft's Windows 8 is also looking interesting. It's scheduled to come out next year (2012) and has a completely new user interface, built around what we're seeing on the Windows phone now.

Paper City Goes Green High Performance Computing - Holyoke, MA

I've been swamped with proposal work - the end of this week is a a major National Science Foundation Advanced Technological Education submission deadline - and have not had a chance to write about the Massachusetts Green High Performance Computing Center groundbreaking in Holyoke, MA held on October 5.

I've written about this project in the past - the idea was launched over a year ago by the Massachusetts Institute of Technology, the University of Massachusetts, Harvard University, Boston University, and Northeastern University. Each school kicked in $10 million and Massachusetts kicked in $25 million from a state fund that provides money to improve roads and other public works to support economic development. At the groundbreaking both Cisco and EMC announced $2.5 million contributions to the project for a total of $80 million committed.

I've been fortunate to have been involved with the planning process (on a technician / workforce / education / economic development level) and it's been interesting to watch the process and progress of the center. Some said it would never happen but - the ground was broken a couple of weeks ago so...... it's happening!

The center has the potential to turn around the first industrially designed city in the U.S. Holyoke was built around a series of man-made canals extending from the Connecticut River that were designed to provide water power to run paper mills. Holyoke once had so many paper mills it's nickname was (and still is) "Paper City". Most of those mills shut down years ago but now - new life for an old New England mill town.

Governor Deval Patrick missed the ground breaking because he was out on Cape Cod, attending the funeral of PFC Clinton E. Springer II who had died in Kabul, Afghanistan on September 24.

The Governor did come to Holyoke after the funeral though and got the chance to attend a Town Meeting following the groundbreaking. We had John Reynolds there with his camera and he got some great video of the Holyoke Mayor Elaine A. Pluta and Governor Patrick.

I don't think I've ever been this excited about a technical project - computers, networks, high-performance research including microbiology, genetics, chemistry, physics..... all performed in a green environmentally friendly way. The economic development potential and the kinds of companies and people the center will attract are potentially huge. It will be very interesting to watch. Pretty cool stuff!

To see more pictures, here's a link to my October 5 event Flickr photo set.

A Good Cloud Computing Video

I was at an excellent Tech Futures Forum event today sponsored by BATEC and CAITE at the Microsoft New England Research & Development (NERD) Center in Cambridge, MA. Edwin Guarin, Senior Microsoft Academic Evangelist gave a nice presentation on cloud computing and Windows Azure. As part of the presentation, he showed the following video:

There is a lot of confusion about what cloud computing is - this video gives a good basic and easy to understand explanation. It's only 4 minutes and 52 seconds long and worh the time to watch!

Cloud Computing Technologies Podcast

On Monday (5/2/10) Mike Qaissaunee and I recorded a podcast titled Cloud Computing Technologies. The podcast references a couple of Infoworld.com documents that we think you will find interesting:

• A short white paper written by Eric Knorr and Galen Gruman titled What does Cloud Computing Really Mean
• A 21 page document titled Cloud Computing Deep Dive Report

The Deep Dive Report breaks down cloud computing into 11 categories and goes into more detail than the shorter white paper. What's really interesting is the categories are different in each document. You can see where the confusion lies when it comes to defining what cloud computing is. Here's the 11 cloud technologies we discuss:

1. Storage-as-a -service
2. Database-as-a-service
3. Information-as-a-service
4. Process-as-a-service
5. Application-as-a-service (a .k .a . software-as-a-service)
6. Platform-as-a-service
7. Integration-as-a-service
8. Security-as-a-service
9. Management-/governance-as-a-service
10. Testing-as-a-service
11. Infrastructure-as-a-service

We also discuss the CloudCamp event (great places to get info and meet people involved in cloud technologies) we hosted at Springfield Technical Community College last month and how you can get information on CloudCamps in your area.


Here's how to listen:

To access show notes and audio of our 23 minute and 26 second audio podcast titled Cloud Computing Technologies click here.

Listen to it directly in your web browser by clicking here.

If you have iTunes installed you can subscribe to our podcasts by clicking here.

CloudCamp Western Mass Invitation

On April 20 the ICT Center and Springfield Technical Community College will be hosting CloudCamp Western Mass.

Never heard of CloudCamp? Here's some info from CloudCamp.org CloudCamp is an unconference where early adapters of Cloud Computing technologies exchange ideas. With the rapid change occurring in the industry, we need a place we can meet to share our experiences, challenges and solutions. At CloudCamp, you are encouraged you to share your thoughts in several open discussions, as we strive for the advancement of Cloud Computing. End users, IT professionals and vendors are all encouraged to participate.

We're fortunate to have some great sponsors for the event including Microsoft, TNR Global, intuit, tropo and the UMass Amherst Computer Science Department.

Here's details on the event:

Date/Time: April 20, 2010, 2:30pm-7pm

Location: 1 Federal St, ICT Center, STCC, Springfield, MA 01105 Directions

Price: Free, food will be served at registration

Who should come: Developers, managers, faculty, students, etc from Massachusetts, Connecticut, Vermont, and surrounding states, who are working with or are interested in working with cloud technologies.

Schedule:

2:30pm Registration & Networking, Food

3:00pm Welcome and Thank yous

3:15pm Lightning Talks (5 minutes each) Sponsors TBD

3:45pm Unpanel (in the same room with lightning talks)

4:15pm Organize the Unconference Sessions

4:30pm Unconference Session 1

5:30pm Food break and Networking

5:45pm Unconference Session 2

6:45pm Wrap-up Session

The event will be technically very interesting and it will also be a great opportunity to network and connect with both national and regional high-tech people and companies.

We'll also be streaming portions of the event out to the web.

Register for the free event by following this link http://www.cloudcamp.org/westernmass/2010-04-20

If there are any questions feel free to email me at gordonfsnyder@gmail.com or call at 413-755-6552