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In 2015, they got a 50 million investment from Grupo Arcano, led by Alberto Chang-Rajii, who is a really shady character who fled from justice for 2 years:

Merged into Quantinuum later on in 2021.

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Honeywell Quantum Solutions by

Ciro Santilli  40 Updated 2025-07-16

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Jeremy O'Brien by

Ciro Santilli  40 Updated 2025-07-16

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www.linkedin.com/in/jeremy-o-brien-39482631

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PsiQuantum founding myth by

Ciro Santilli  40 Updated 2025-07-16

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Once upon a time, the British Government decided to invest some 80 million into quantum computing.

Jeremy O'Brien told his peers that he had the best tech, and that he should get it all.

Some well connected peers from well known universities did not agree however, and also bid for the money, and won.

Jeremy was defeated. And pissed.

So he moved to Palo Alto and raised a total of $665 million instead as of 2021. The end.

Makes for a reasonable the old man lost his horse.

www.ft.com/content/afc27836-9383-11e9-aea1-2b1d33ac3271 British quantum computing experts leave for Silicon Valley talks a little bit about them leaving, but nothing too juicy. They were called PsiQ previously apparently.

The departure of some of the UK’s leading experts in a potentially revolutionary new field of technology will raise fresh concerns over the country’s ability to develop industrial champions in the sector.

More interestingly, the article mentions that this was party advised by early investor Hermann Hauser, who is known to be preoccupied about UK's ability to create companies. Of course, European Tower of Babel.

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Con of superconducting qubits by

Ciro Santilli  40 Updated 2025-07-16

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requires intense refrigeration to 15mK in dilution refrigerator. Note that this is much lower than the actual superconducting temperature of the metal, we have to go even lower to reduce noise enough, see e.g. youtu.be/uPw9nkJAwDY?t=471 from Video "Building a quantum computer with superconducting qubits by Daniel Sank (2019)"
less connectivity, normally limited to 4 nearest neighbours, or maybe 6 for 3D approaches, e.g. compared to trapped ion quantum computers, where each trapped ion can be entangled with every other on the same chip

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Pro of superconducting qubits by

Ciro Santilli  40 Updated 2025-07-16

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16S ribosomal RNA by

Ciro Santilli  40 Updated 2025-07-16

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5S ribosomal RNA by

Ciro Santilli  40 Updated 2025-07-16

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23S ribosomal RNA by

Ciro Santilli  40 Updated 2025-07-16

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EF-Tu by

Ciro Santilli  40 Updated 2025-07-16

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PostgreSQL getting started by

Ciro Santilli  40 Updated 2025-07-16

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On Ubuntu 20.10 PostgreSQL 12.6, login with psql on my default username without sudo fails with: stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-exist

This is the one that worked on Ubuntu 21.04: stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-exist/38444152#38444152

sudo -u postgres createuser -s $(whoami)
createdb $(whoami)

Explanation:

sudo -u postgres uses the postgres user via peer authentication
-s in createuser -s: make it a superuser
createdb: TODO why do we have to create a table with the same name as the user? Otherwise login fails.

You can now run psql without any password. This works without password due to peer authentication:

sudo cat /etc/postgresql/12/main/pg_hba.conf

shows that peer authentication is available to all users apparently:

local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer

List users:

psql -c '\du'

output:

                                    List of roles
  Role name  |                         Attributes                         | Member of
-------------+------------------------------------------------------------+-----------
 ciro        | Superuser, Create role, Create DB                          | {}
 owning_user |                                                            | {}
 postgres    | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

Delete user later on:

psql -c 'DROP USER username;'

Create a database:

createdb testdb0

Help toplevel:

help

Get help for Postgres commands such as \h and so on:

\?

List supported SQL commands:

\h

Show syntax for one type of command:

\h SELECT

List all databases:

psql -c '\l'

which shows:

    Name     |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-------------+----------+----------+-------------+-------------+-----------------------
 ciro        | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 |
 postgres    | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 |
 template0   | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 | =c/postgres          +
             |          |          |             |             | postgres=CTc/postgres
 template1   | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 | =c/postgres          +
             |          |          |             |             | postgres=CTc/postgres
 testdb0     | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 |
(6 rows)

Delete a database:

psql -c 'DROP DATABASE "testdb0";'

If you didn't give a database from the command line e.g.:

psql

you can do that afterwards with:

\c testdb0

Let's create a table and test that it is working:

psql testdb0 -c 'CREATE TABLE table0 (int0 INT, char0 CHAR(16));'

List tables, no special tables:

psql testdb0 -c '\dt'

gives:

        List of relations
 Schema |  Name  | Type  | Owner
--------+--------+-------+-------
 public | table0 | table | ciro
(1 row)

View table schema: stackoverflow.com/questions/109325/postgresql-describe-table

psql testdb0 -c '\d+ table0'

output:

                                      Table "public.table0"
 Column |     Type      | Collation | Nullable | Default | Storage  | Stats target | Description
--------+---------------+-----------+----------+---------+----------+--------------+-------------
 int0   | integer       |           |          |         | plain    |              |
 char0  | character(16) |           |          |         | extended |              |

Insert some data into it and get the data out:

psql testdb0 -c "INSERT INTO table0 (int0, char0) VALUES (2, 'two'), (3, 'three'), (5, 'five'), (7, 'seven');"
psql testdb0 -c 'SELECT * FROM table0;'

output:

 int0 |      char0
------+------------------
    2 | two
    3 | three
    5 | five
    7 | seven
(4 rows)

Delete the table:

psql testdb0 -c 'DROP TABLE table0;'

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Create a test user in PostgreSQL by

Ciro Santilli  40 Updated 2025-07-16

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In order to create a test user with password instead of peer authentication, let's create test user:

createuser -P user0
createdb user0

-P makes it prompt for the users password.

Alternatively, to create the password non-interactively stackoverflow.com/questions/42419559/postgres-createuser-with-password-from-terminal:

psql -c "create role NewRole with login password 'secret'"

Can't find a way using the createuser helper.

We can then login with that password with:

psql -U user0 -h localhost

which asks for the password we've just set, because the -h option turns off peer authentication, and turns off password authentication.

The password can be given non-interactively as shown at stackoverflow.com/questions/6405127/how-do-i-specify-a-password-to-psql-non-interactively with the PGPASSWORD environment variable:

PGPASSWORD=a psql -U user0 -h localhost

Now let's create a test database which user0 can access with an existing superuser account:

createdb user0db0
psql -c 'GRANT ALL PRIVILEGES ON DATABASE user0db0 TO user0'

We can check this permission with:

psql -c '\l'

which now contains:

                                  List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
 user0db0  | ciro     | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 | =Tc/ciro             +
           |          |          |             |             | ciro=CTc/ciro        +
           |          |          |             |             | user0=CTc/ciro

The permission letters are explained at:

user0 can now do the usual table operations on that table:

PGPASSWORD=a psql -U user0 -h localhost user0db0 -c 'CREATE TABLE table0 (int0 INT, char0 CHAR(16));'
PGPASSWORD=a psql -U user0 -h localhost user0db0 -c "INSERT INTO table0 (int0, char0) VALUES (2, 'two'), (3, 'three'), (5, 'five'), (7, 'seven');"
PGPASSWORD=a psql -U user0 -h localhost user0db0 -c 'SELECT * FROM table0;'

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 Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.

Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!

Video 1.

Intro to OurBigBook

. Source.

We have two killer features:

topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
Articles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1.
Screenshot of the "Derivative" topic page
. View it live at: ourbigbook.com/go/topic/derivative
Video 2.
OurBigBook Web topics demo
. Source.
local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
Figure 2.
You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website
.
Figure 3.
Visual Studio Code extension installation
.
Figure 4.
Visual Studio Code extension tree navigation
.
Figure 5.
Web editor
. You can also edit articles on the Web editor without installing anything locally.
Video 3.
Edit locally and publish demo
. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
Video 4.
OurBigBook Visual Studio Code extension editing and navigation demo
. Source.
Internal cross file references done right:
Infinitely deep tables of contents:
Figure 6.
Dynamic article tree with infinitely deep table of contents
.
Live URL: ourbigbook.com/cirosantilli/chordate
Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade

All our software is open source and hosted at: github.com/ourbigbook/ourbigbook

Further documentation can be found at: docs.ourbigbook.com

Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact

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